It would be extremely unwise to let them push LTE-U thru without lots of independent testing and analysis. Even then there is a case to be made for keeping some spectrum 'open' and unlicensed lest we see it all end up owned by a handful of corporations.
I think this is the important point. Let cell carriers in and they will subscribe as many people as necessary to fill the available bandwidth. After all, that's pretty much what they are paid for.
It's like road congestion - the amount of suffering depends on people's tolerance to endure suffering, not on the amount of available resource. There will always be more people willing to watch lolcat videos on their phones if they don't stutter too badly.
Keeping some spectrum aside from big operators allows at least small LANs to operate reasonably, while opening it to them may easily end up bringing suffering to everyone.