It's an interesting theory, but selling the game for a higher price would drive away people who are slightly interested but not interested enough to pay full price, not to mention those who already own the game twice (or three times if you're the kind of person who bought the GD ROM). Adding to that the increased production costs of the medium and the additions you suggested, I'm skeptical to say the least.It's reasonable to assume Treasure would've sold more copies had they sold Ikaruga on a standard Xbox disc with more content or options -- for example, bundled with RSG or even Appreciate-style replays (although the leaderboard is pretty damn sweet). They'd make a killing because of the media used and the higher level of accessibility.
Wikipedia says that the DC version only had 50k copies made, so it likely didn't sell more than 100k. The Gamecube version apparently sold ~25k before falling off the charts in Japan, and I'm skeptical they've doubled the sales of that since then. No clue how it did outside of the US but I'm assuming not as well in Japan. I'm not able to find concrete sales for the GC version, but I wouldn't be surprised if the XBLA port has outsold both of them, not to mention the fact that it's still actually for sale.
(Wiki indicates that the Gamecube had more units sold by the end of its life than the 360 currently has so I don't think the choice of console hurt it terribly.)
Enough that Treasure doesn't have the resources to throw away for minimal returns?But again, how many resources are being tapped to port an old arcade game to one of the most developer-friendly consoles out today?
According to wikipedia they're a 30-40 person company that is apparently broken up into three teams. Assuming they're evenly divided, they have about ~13 people per team. It's probably safe to say that they're not overflowing with people looking for something to do.