I think it is very important for mums to have me time. Could it be that BF moms are more attached to their babies and unable to leave them? (Toria, Sam's mum, Tasha, Marley???) I might be fishing here, and I don't wanna say that we, bottle feeders don't care as much for their babies. But maybe it is the fact that only YOU can give your baby what he/she needs is what makes you feel that it is not even necessary to leave your baby alone every once in a while.
I love Mia more than anything, but I work full time, 8-4 every day, while she is in good hands at home. I completely trust the people taking care of her, and they can always contact me at work if something is wrong. There is nothing better than coming home after work and seeing her smile. Absolutely priceless. Makes it all worth it.
Also, she spends almost every weekend at Grandma's. It is not because I ask for the time "off", but because her grandparents adore having her over and she always learns something new when she returns.
Again, I don't think there is anything wrong with having alone time.