The main thing to remember with this is that even if you do end up with a % of people who do just bum around on basic, a lot more still would rather earn enough to live a more interesting life. And wages will probably go up to incentivize people to do the crap jobs - or encourage someone to find a way to automate it.
Hire when business is booming
Send people home when business is slow
No tears if you let someone go
No more billing the customer for employees who do nothing
More skilled people to hire
Training employees for the price of training
More people to chose from
No more minimum wage(!)
Free employees who want to learn
Honest short job interviews (starting wages as low as zero)
No more complex pension plans
No more complex insurance
Less medical tests
No more unreliable temp employees
No more employees who hate you with a passion
Less theft and vandalism
A lot more customers as the economy now works for human beings
A lot more businesses to buy from and to sell to as anyone can now start a business
More competition thus more efficiency
More social interaction and empathy
And (I jokingly add) Incentive for employers to stop acting like assholes
And the social benefits and savings are also huge: We could stop breeding massive amounts of criminals whose annual cost is equal to four years at Harvard[1] Police officers would be able to do their job without fear of being killed and without killing people. But the greatest social and economic accomplishment is to set people free from the life of fear that is job insecurity. People can stop living from day to day, dream the big dream, learn what needs to be learned and accomplish the big dream. This might be hard to imagine if you have a nice life and know nice people who are doing well for themselves. But even then you know how nice it is to have help from friends who believe in accomplishment. A few words of encouragement, a bit of help with your weaknesses. Ohh it is a world of difference from being surrounded by people who believe in failure because they've seen nothing else. Imagine the kind of help you would get from friends or relatives who just want to get drunk or high simply to forget what miserable lives they have. They will be there for you every day to remind you that whatever it is you are trying to do won't amount to anything - and then they will enjoy your failures.
Not unlike the people who don't want to see a basic income because other people might enjoy their lives. Those of us who want to build a modern, functional, resilient and happy society have to work with these people who want nothing more than to see others suffer. shrug
[1] - http://www.nydailynews.com/new-york/cost-inmate-nyc-ivy-leag...