There have been lots of improvements to low levels that address your concerns. To wit:
buggerall attacks for a long time. (As a tanker or defender it's not uncommon to have one single weak attack until the mid-20's or so, and much twiddling your thumb while you wait for it to recharge.)
Having a single attack is not just uncommon, it's downright impossible. You get brawl and a ranged attack as inherents. They become useless soon, but at the low levels they are indeed quite useful. Brawl does about 20% of an enemy's HP at level 1. And it recharges in 2s. The ranged inherent does about 15% of the enemy's HP, and has a secondary effect (a debuff, sleep, hold... to get people familiar with these things). So at the low levels you're in fact pretty well equipped for the low level weak enemies.
A single weak attack till the mid 20's also sounds really bizarre because that'd imply getting nothing but powers from the "non-attack" part of your powerset and non-attack pool powers constantly (as there are levels where you will simply not have a new power from the primary open up for you, and then you'd have to choose a non-attack power from the pools), technically you CAN do it, but you'd be quickly advised by anyone you care to ask in-game about making a more balanced power choice - and the community is rather friendly that way. If you messed up the build the first time, not to worry, you now can have a second build for your character, so the newbie can switch to the second one and re-do it with more knowledge at no cost.
Also, you don't have to "waste" a power choice to travel around at the low levels. As soon as level 5 you can do a safeguard/mayhem mission to acquire a temporary travel power, then again at 10, and that will easily last you into the 20s. And if you are a villain, you can just buy a temporary jetpack outright as often as you want (the heroes have the contact for this locked in a hazard zone, which is a rather bizarre idea, but there you go).
you run out of endurance (think: mana) within a fight, and the "rest" button recharges once in a blue moon, so mostly you just get to sit around twiddling your thumbs for 3 f-ing minutes until it slowly recharges. And it gets even worse if you actually use your defenses, because those suck your endurance even faster.
Rest now recharges (unenhanced) in three minutes, so unless you just used it and want to immediately use it again, you don't have to wait for 3 f-ing minutes - and a single dual origin enhancement will put that at 2m30s. At the rate things go at low levels, you have it available every other fight or so, it's rather uncommon to need it much faster, and if you start with full end and HP bars, I doubt you'll have to wait much more than 30s to use it when you've finally gone through all your HP and need it again.
At the very low levels you'll hardly have any need for your defense toggles. That is pretty much evident after a couple of fights for any new player.
get to run to the other end of a zone and back all the time, and often through enemies which can kill you easily (running into level 6 enemies when running to a level 1 mission is not really great fun. And as that level means, it's more like running through level 10 enemies on WoW.)
A level 1 character is, first of all, someone who skipped the tutorial, where you get to level 2 quickly and safely and learn about the game - something a newbie or a trialer will likely not do. Second, your starter missions will NOT send you into the red zones of the starter areas - which is where the level 6s lurk. Third, Most everything CoV and all the better streamlined areas in CoH will not have you running back and forth, the contacts will give you their phone number after a mission, maybe two.
your accuracy sucks, so you'll have big streaks of missing the enemy
Your accuracy is 90% at level 1 thanks to the "beginner's luck" buff that slowly diminishes as you level up - and there is the obvious case of accuracy enhancements AND inspirations. Moreover, there is a streakbreaker code, if you miss twice in a row at that accuracy, your third attack WILL hit.
The streakbreaker depends on your overall accuracy, with beginner's luck you will only miss twice in a row before it kicks in until it has gone lower than 80% at level 12-ish, at which point it will let you miss thrice in a row. IF you actually use accuracy enhancements and go over 90% chance to hit (which, with the low level buff, is trivial), you will only be allowed to miss once before the streakbreaker hits.
The streakbreaker has been in-game for a long long time. The to-hit buff at low levels is more recent.
you only need to take one wrong turn to wake up at the hospital
If by wrong turn you mean hoofing it from the beginner's contact to the clearly marked red zones in the starter area or ignore the warnings of "THIS IS A HAZARD ZONE!", I suppose you're right. Even hazard zones are getting tamer, the Hollows, the "nice low level zone" per excellence, was even made easier to navigate by getting huge reductions in the amounts of street mobs you find.
Many of your complains about low level mobs are an inspiration away from being trivial - inspirations that are almost free from any of the contacts giving you those missions, - including that evil evil singularity. Ah, and that example is specially bad because you make it sound like it's a generalized thing. There are precious few mobs at low level with a big array of abilities (Elite Bosses... Which are equivalent of an elite quest in WoW), and if you really can't get through by using a few inspirations, well, guess what? You can autocomplete the mission. There is a limit to how often you can autocomplete - three days. Which is more than enough to get through those very hard elite bosses, because at low levels you just don't find them left and right. Of course you could also team, but it's not even necessary.
Skipping to the end now:
Will the mission architect help there? I doubt it
You have been specifically complaining about "level designer idioticy" in your post, and then don't agree that the Architect can help? It will be possible to design entire factions now, give them whatever powers you want. You can make factions for your low level missions that don't have endurance drains or to-hit debuffs. The missions are streamlined with zero travel time and no "finding purple mobs at the wrong turn while travelling to the mission". Don't like Elite Bosses at the end? Don't put them there. There will be a rating system to make it easier for the new user to go and select the good/enjoyable creations. The potential to solve many of your complains is HUGE.