Then your enemy's not playing right. A horde of small/medium units should have been able to wipe out your base while you were building up to your uber units. Unless you were only playing against the AI, in which case you probably shouldn't have been expecting a challenge anyway :)
Exactly. Try playing against humans and see how quickly your strategy will change - if you reached Tech3 in 30 minutes before, expect to be barely hanging on at Tech2 after 1 hour...
THIS WILL HELP. [GPG]
Don't be offended by the title - I always played SupCom by slow, quiet research followed by the same old blitzkrieg and got bored pretty quickly. You'll be surprised how intense and stressful a game can be when you play by going for blood rather than immediate research, not to mention how quickly your game (and adaptability) will improve.