Tablet, cellphones. Show me how to produce all of the symbols on a standard keyboard on an iPad, Android tablet, cellphones, etc. without a custom keyboard installed. Now show me how to do it with close to 100% reliability on a virtual keyboard or tiny chicklet keys that aren't your usual device. That's one reason for using common characters only works. Also, see: internationalization- staying with a lowest common denominator saves you from some of the various physical keyboard and charset bastardizations that are floating around.
Long ago, strong anonymity wasn't a big feature but handles/pseudonyms were certainly common around BBS times.
For electronics, the big differentiators between things like iPads and dedicated nav gear are resistance to abuse+moisture and lower electrical power consumption, plus use in a variety of conditions: light, dark, spray/rain, ability to use the interface with wet and gloved hands, etc. Being able to have a big reserve of AA batteries to run your handheld GPS and similar gear is also much more robust than counting on being able to recharge your phone or tablet if your diesel goes kablooey. It also avoids the necessity for a charge cycle.
The advantages/point are usually things like being able to do a relatively small amount of coding to produce a very useful tool (such as a plugin for PhotoShop, in which you avoid duplicating a prohibitive level of effort to add a small increment of functionality) or in which the users of that other companies service are specifically the target (app for Facebook: what the app developer actually wants to do is provide a small addon to an existing large audience, not to start a different social network people would have to sign up for). Yes, FaceBook app developer is quite dependent on FaceBook, but no more so than many other businesses which start out and sometimes continue to operate with a large amount of dependence on one key supplier or one customer (or a small number of them).
I would hope that courts wouldn't accept a claim that interoperability defenses are void if an API function call (at the compiled executable level you need to link to) happens to be named after a particular vendor or requires you to pass the brand name of a particular vendor into every call and that only people they license to use their name are allowed to use it in that context.
Your example involves users being able to impersonate other users, not users being pseudonymous. Sending email from a server which appears to come from a particular account is generally something that the server operator would want to control. That problem is about "Bob Smith" being able to effectively impersonate "Jim Carpenter", not a question of whether "Jim Carpenter" is allowed to have a username of "bikerdude". The latter has been very common in lots of tech social circles for a very long time (BBS's, whimsical email addresses, etc.). Other social circles require real names- either by preference or because it seems objectively useful to the participants to know what physical person they're dealing with (such as who they can pursue for restitution if a purchase of used hardware goes bad).
When a court hasn't ruled yet, you might argue that the situation is unclear before a definitive court ruling if you've got competent legal authorities arguing in different directions. It isn't correct to say that something isn't illegal just because a court hasn't ruled against anyone doing exactly that thing yet.
Gladly? Give credit where credit is due: the word "compulsory" in "compulsory legal request" seems to mean that they'll comply with something like a legitimate subpoena (and what business wouldn't?) but not with "Well, we don't have any legal right to demand this information, but would you mind giving it to us anyway?"
Mandated was far too strong a word for the poster to use, but the general concern about likely results (intended and unintended) is legitimate. Legalizing assisted suicide would definitely open up some related questions about competence, conflict of interest, and general social policy for both public entities (courts, legal guardians, tax entities, etc.) and private interests (family, insurance companies, etc.).
re: marriage - The government certainly structures taxes in a manner which encourages certain kinds of family structures and discourages others. Even if nothing is done intentionally, there might be some unintended consequences with regard to tax treatment of dependents, etc. even before you get into whether legal guardians would have the authority to make such decisions on behalf of their wards.
Depending on how you do the weighting, Canada could still come out behind. Among other things, it has done much more than the US to forbid reporting of some current legal proceedings. Obviously, it's a really subjective list (some countries should obviously rank poorly because they're bad on all or almost all metrics, but it's much less clear near the "free" end of the list which factors should matter the most).
For now, centralizing computing resources in "the cloud" doesn't have the same obvious and conclusive upper hand in the vast majority of common uses that centralized electricity generation does. Some fundamental shift in economics of power generation (such as extremely cheap and durable solar panels) might change the situation, but that hasn't happened yet. For comparison, lots of individuals and businesses at all size levels find local computing resources to be the best solution for them. Even massive consumers of electricity don't generally choose to build and operate their own power plants.
Conflict among friends is something a social site usually tries to avoid. People tend to take it personally if they post an opinion/political/social link and start getting negative feedback. The possibility of a written comment which disagrees is unavoidable if you allow comments, but a "Dislike" button would probably make a lot of users unhappy without a proportional benefit. That's bad for business on a social site which depends on networks of friends staying happy and not hesitiating to post things.
It's not necessarily legal to listen to (and archive) radio transmissions which aren't intended for you, even if they are sent unencrypted. There's a big difference between a television station and a private wireless computer network or cordless phone.
Logical extensions to "common carrier" status would seem to outlaw many/most business abuses without restricting technical mechanisms or preventing innovation.