Hood placement should be based on Rank & Age - Both need to be considered!
More criteria means less flexibility. Each player will match to fewer potential neighbours. That runs contrary to the point of the neighbourhood merges, which is to bring each player into contact with a multitude of other players, rather than the same players over and over again.
There are also unintended consequences:
- Trade in low score neighbourhoods will be abysmal. The players will be less active, and have fewer goods to trade.
- Players in low score neighbourhoods will have fewer GBs to invest in, and get fewer investments to their own GBs. They'll be entirely dependent on high score guild members and FL'ers for BPs, FP packs and medals.
- Aiding will be lower in low score neighbourhoods, as they will have less active players.
- Many FL'ers will be people who have been in the same neighbourhood; for players in low score neighbourhoods, that means less active FL'ers, with fewer GBs.
Making things worse, it quite possibly won't help much against plundering. The score in itself says very little about military strength and capacity. When it comes to inclination to plunder, players with well developed cities have a much lesser need for it. An Arc will give a very high score, but no military benefits. Rather than being a threat, a high Arc in the neighbourhood results in more donations to buildings, and the opportunity to get Arc BPs. The same and similar goes for many other "peaceful" GBs. Meanwhile, most of the military GBs give relatively low scores; you can have a pretty high Zeus, CoA and CdM, with limited effect on the score.
For the majority of high score players, I actually fail to see any real drawback. On the contrary, they'll benefit from the opposite of these negative effects. That will more than outweigh the loss of the occasional limestone or ebony plank.
Personally, I think this would be a disaster for the lower score players, and for the game as a whole.