Has anyone noticed that besides Metroid and Mario Tennis the games are really small games that ONLY attracted the core fanbase?
I don't think Mario Power Tennis sold very well; it never became a Player's Choice title. However, sales data for any game which didn't sell more than a million copies is practically impossible to find. According to Wikipedia, of the seven New Play Control! titles Metroid Prime and Pikmin are the only two which sold more than a million.
Pikmin probably wasn't as well received as Nintendo had hoped. The re-releases of the two Pikmin games exist to garner attention for the series so the release of Pikmin 3 has a better chance of being met with success. Now, I've never played Pikmin and I'm not sure if it's something I'd like, but the series seem unique and deserves to become one of Nintendo's main franchises.
Chibi-Robo and Donkey Kong Jungle Beat are both obscure titles released near the end of the purple box's market life, so re-releasing them onto the Wii and its larger market make some sense. I'm not so sure these titles are aimed solely at Nintendo's new market however, as there are plenty of GameCube owners who passed on the titles. If they perform well the second time around, hopefully we'll see some sequels.
Metroid Prime 1 and 2 however, are just cash-ins. Metroid Prime 3 was a moderate success, so the first two games are being re-released to take advantage of that. They aren't experiments because MP3 got the controls right, and they won't have any affect on any possible future Metroid game for Wii.
Mario Power Tennis is a cash-in as well, targeting the Wii Sports crowd. Mario games which aren't Mario Strikers have achieved huge success on Wii, and a new Mario Tennis game would have pretty much been a guaranteed hit. Other Mario games -- including ones which sold poorly on GameCube -- received sequels on Wii, so why not Mario Tennis? Because Camelot isn't interesting in creating Mario games anymore, so Nintendo is re-releasing MPT. Sadly it probably means we won't be seeing a new Mario Tennis on Wii, since by that time there will not only be plenty of other tennis games out there, but also a plethora of Mario games.
I'm just calling this one as I see it. I can't say I'm against the re-releases seeing as I purchased Mario Power Tennis and will probably get a couple of the others as well. I can envision good coming from this, but I can also envision more re-releases. A mixture of both is probably the likely result. Who knows what Nintendo's real motivations are behind these titles, be they experiments or cash-ins or both. Either way, I'm not expecting anything, so I'll be happy if they result in something like sequels but won't be disappointed if all that happens are more re-releases.