Well, it's their sims, they can do what they want. I've already seen the ones I cared to see anyway. I personally like to stay in my own sim, so no big deal here; I usually don't like exploring in the first place. It's too bad for other people though if they start to charge for all sims. Many can't pay since they're too cheap to spend money on
SL 
, or won't pay as they are too cheap in general.
If it's money they need, they could get some of those sim creators making more stuff to sell, or just don't open a bunch of sims you can't pay for in the first place.
Anyway, whatever.