Yep, I've argued this point for a while.
Unless your a superstar on youtube, daily uploads are too much, people just don't want you in their life everyday.
Now with so many viewers on cell phone, it becomes like an annoying spam event, ever bought something and gave your number then that company bugs you all the time with 10% discounts or whatever? youtube is similar, subs want to watch your stuff but geez, everyday?
They probably have 50 channels they sub to, it would be so annoying getting pumped with your video's day after day after darn day.
So i'd imagine they would unsub and think, i'll just catch up with that channel when I think of it from now on, as most likely it's not their favourite.
Not to mention the strain it must take to put up a vid' everyday, unless the vids are just no brainer vids but even then, it must be pressure to get one up everyday,
publishers need a break from themselves just like your subs do.