That's a lot of questions.. :)
- Bot's can provide an important service, and have been (indexing). With the site developing (Following lists...etc), they need to evolve to continue to be 'useful'
- Nothing stopping anyone at the moment. as they get more complex, it will become more difficult for the average user to replicate the intricacies of the 'black box bot's..'
- The experience will be better with bots in my opinion. It'll just take time for them to become as useful as they can be...