i've been kegging for a few months and love it. i didn't bottle for very long, but when i did bottle 100% of my batch it really wasn't that much of a pain. i suppose now i have to answers the numbered points:
1. yep, it costs money. more money on top of the money we've already spent. a CO2 cylinder and regulator will total about $100- $150, corny kegs are at least $25 and often as much as $40, and then you have to replace all the orings for $5 per keg. your kegerator or keezer will cost at least $100, depending, and add another $50 or so for each faucet and parts needed. that's a lot of money. if you can't afford it that sucks, but if you can then it might be an expense you're willing to endure.
2. most adults are able to ration their own consumption and even keep a count inside their own heads!! if you can't, see
here.
3. i always bottle at least a 6pack for the vault and for comps, etc. it's very easy to do, even easier than bottling from a bottling bucket. see
here.
4. like you mentioned, natural carbonation can be done in a keg, but i don't see how bottle conditioning is better than forced carbonation. the CO2 doesn't know where it came from. i can say that with bottle conditioning you must wait for the yeasties to finish their business. i just racked a porter into a keg last night, gave it 35 psi, and went to shake it during commercials while i watched a movie. left it on the gas overnight and i'm drinking one right now. delicious.