Have people considered nominating a group of trusted people in the community that people can lease their forging power to?
If there was an open market for leasing(is there?) I think that would be a bad thing in general. As it would allow an attacker to gain more forging power than they would be entitled to by actually having to buy up all those coins(which is a big part of the security behind PoS). Just like now in PoW anyone who knows how and has a few BTC can attack any number of blockchains that aren't strong just by renting some hash for short period. In this regard PoS is much more superior, but only if an attacker can't similarly acquire forging power as people can now rent hashing power.
It is an open market and will stay that way. If the implementation was limited in Nxt core someone would code it as an addon. Having a "trusted group" as the only party people can lease their forging power to would break the principle of decentralized trust free network.
EDIT:
But IMO there's no point to forging pools in the first place, or in fact they are very bad already. Leasing your stake is easier than forging by yourself, which leads to lower number of forgers and a weaker network. You actually
lower the network's security by leasing out your stake, and
get paid for doing so.