Any individual player can be a host for a game. I have no problem with keeping up with those games since I make an icon to take me to each one. All I have to do is click thru them each day. You could also make a web page on your own machine very easily which lists your games.
I have offered to do a multi-game server on my linux server. Im still interested in trying it myself in a slightly different form than Mosehanson has done.
As for Shrapnel doing a server, they have offered to do that. But it wont be a "they could easily do". It will be "when one of us makes a stable server". When the server project here is alittle farther along then those discussions may kick up again. The same with the PBW server project which is going on in the Space Empires IV forum (also a Shrapnel forum).
Pros and Cons. Shrapnel runs Windows servers. A Linux server could be done cheaper but it would be new territory for them. I think the best possible answer would be for someone to do a simple generic PbEM site which could handle both Dom2 and SEIV games (and any others that Shrapnel picks up)