But the other players beyond those three have to also have an internet connection and a system and the game. To play a 16 player game (and thus to 'get the most out of it'), the cost is a lot higher for PD0 online or Mario Kart DS online than for FF:CC/Connectivity was. It may be less accessible for most, but cost sould not be a factor. One player needs a TV, a GCN, the game, their GBA and a Link Cable ($360) The other players bring over their GBAs that they already own (not ones that they bought *just* for this game) in order to play multiplayer. Either the GCN owner or those with the GBAs can supply the link cable.
The only real complaint (cost wise) would be about the Link Cable. Yeah, those with GBAs and without a GCN (or just without a use for the cable) won't want to buy the cable, so there a possibililty for an extra $15-$60 cost for the person who owns the game. I can't really defend that part of it (although, again, it's all cheaper than the total cost of other "online" games).
Personally, I've got five Link Cables and only ever purchased one of them - so really, the cost didn't have to be high. My first cable, I ordered from Nintendo (the only way to get them when they were first offered for Sonic Advance/Sonic Adventure 2: Battle). My second one came free with my Pokémon Colosseum Pre-Order that I never picked up ($5 down for the bonus disc and a link cable - I couldn't pass it up). My third one came free with FF:CC, my fourth came free with Zelda: Four Swords Adventures and my fifth came free with my imported FSA (had to get Tetra's Trackers!). Granted, I don't expect everyone to have managed to get all these free Link Cables the same way I did, but considering Nintendo gave so many away (also, there was a GCN bundle that included Wind Waker and a GBA/GCN link cable), to claim that they were hard to get/cost too much just doesn't sit too well with me.
Now if you want to complain about how hard it is to get three friends with GBAs to come over vs. getting three (or more) people together online, yeah, that's a valid complaint. Heck, I have a hard enough time working out a schedule to get two or three friends without GBAs to come over to play regular multi-player games. But again, if you can't get people to play games at your house, would you buy the next Mario Party game? No, it's not for you. The same with FF:CC - it just simply wasn't a game for everyone. It was a game for people with friends who had GBAs. Period.