RainbowDespair:

Or compare it to Splosion Man which, like Supercow, has high quality presentation values and 1-button platformer gameplay, but unlike Supercow has excellent level design & a ton of style to back it up.  The result is that Splosion Man is one of the most enjoyable games I've played all year

Ditto. I don't often buy platformers, but I bought Splosion Man a couple minutes after trying it out.

RainbowDespair:

Captain Comic:

On the other hand Super Cow is one of the most professional titles and it apparently hasn't done well.

I think it's important to distinguish that professional and enjoyable aren't necessarily connected.  Supercow looks professional with its high quality graphics & UI, but the gameplay is about as bland as platformers get.  Heck, it didn't even manage to keep my 8-year old's attention for the entire 8-minute trial time.  Contrast that with something like Miner Dig Deep which doesn't look very impressive, but has done rather well on the strength of its enjoyable gameplay.  Or compare it to Splosion Man which, like Supercow, has high quality presentation values and 1-button platformer gameplay, but unlike Supercow has excellent level design & a ton of style to back it up.  The result is that Splosion Man is one of the most enjoyable games I've played all year and Supercow was almost instantly forgettable.

It's important to judge games with public perception in general as opposed to your personal anecdotes. What one person finds fun, another person may hate. For instance, I don't think anyone here likes RC Air Sim, it's about 3 generations back in the graphical department, and yet it's the most successful game on the service.

Instead, it's probably more important to look at the STYLE of gaming that the public seems to like in general and compare that to what's available. Castle Crashers is popular, partially because of the hype, but also because of the level gaining, personalization via possessions, and collection aspects, which seem to be extremely popular combined with the multiplayer nature that encourages friends to also purchase the game to play with friends. There isn't really anything on IG like that to that degree, and anything in the genre that IG has doesn't have online play or level progression. In any comparable example of a non unique game, IGs are missing features that the more popular XBLA games have, and we aren't talking achievements, either. And a lot of those features may make the difference.

arrogancy:

The Shape of Games to Come:

arrogancy:

3) Size limitations, lack of gamer interest, content prohibitations, and pricing limitations are making it more and more unattractive to many indie devs for various reasons, yes. It's good for casual and app development as of now, though.

XBLA has at various points dealt with all of those issues, except possibly for the lack of interest, and yet games on the platform are generally much more successful, so I don't think those particular limitations are a likely explanation. 

Those are all issues that developers at www.tigsource.com, www.indiegames.com, www.gamedev.net, as well as non game focused forums like the somethingawful forums have expressed, where many devs gather, many of which have successful and highly rated PC games games under their belt, express for not wanting to create a game for XBLIG and instead focusing on other methods and going the C++ route for easier porting.

Size limitations - XBLA initially had a size limit of 50MB, which was bumped to 150MB, which was bumped to 350 MB and I think that's where it stands now.
Content prohibitions - is there a single XBLA title that would be banned on XBLIG due to its content?  I can't think of any.
Pricing limitations - yes, pricing on XBLIG is limited, but it's also (and always has been) limited on XBLA as well.  One of the things that came up during the debate about Braid's price was that Microsoft had much more say in the price point than Jonathan Blow did.

I'm not going to argue about whether or not people are making those arguments, but anyone who is arguing the XBLIG can't be successful because of those restrictions should have been saying exactly the same thing about XBLA titles, which, especially in their early days, faced very, very similar restrictions.  Since a number of XBLA games managed to be very successful under the same limitations, the only reasonable conclusion that can be drawn is that the limitations are not the factor limiting sales.

They are in a sense if they are limiting (proven) developers from creating games for it, whether their opinion is warranted or not.