What a sad, sad topic. I can't see how a true gamer could disagree with the OP, and the best argument for that position is "look at the top 50." Well, go ahead and look at it. When a core game with real effort put into it hits the system it does pretty well. Monster Hunter has been deemed "too Japanese to sell in the West" for a long time, but it's top 50. And look at CoD. When they bother to release a game day and date it does pretty well. The problem is that most people who play CoD are social (aka "casual") gamers who buy every year to keep up with their friends, yet the Wii doesn't get the latest CoD every year. Of course CoD would sell poorly on a system where CoD doesn't get full-hearted support.
Now go beyond that. Name some games that undoubtedly would have been top 50 on PS3/360 that were released on the Wii. Anything? Don't say Conduit, because as much as I like HVS's moxie they didn't deliver a product that would have sold any better with the mere addition of HD graphics. Don't say Madworld or No more Heroes, because they were niche titles. Name one attempt to make a game that had everything, and I mean everything, in place so that they would have sold on an HD system but also got an SD version and failed miserably. You can't do it.
There was no lack of hardcore gamers on the Wii, just a lack of hardcore support. On the rare occasion that a big title hit Wii as well as its competitors, at the same time and without business decisions that failed to build the proper level of support, the Wii version stood up for itself and sold. The only thing that has held back hardcore games on the Wii has been the third parties. And to ask them to stop shooting themselves in the foot is really just a courtesty. If Modern Warfare launched on the Wii day and date with all other versions, every other CoD would have sold much better on the Wii than they did because the people who just want to keep playing with their friends could have. If semi-failures like Mirror's Edge would have done that they may have squeked out enough sales to get another sequel. If guarenteed hits like GTA4 would have done that the companies would have walked away with a few hundred million dollars to make their next product.
Instead 3rd parties ignored the Wii, and at best threw the least they could its way. They made games that never made much sense (Deadly Creatures, anyone?). The made late ports (RE4, anyone? Oh wait, that sold pretty god damn well despite the disadvantage!) They made on-rails shooters out of their "core" products (DSC and Extraction anyone?) instead of providing the games people actually wanted to go out and buy. They never gave the Wii a fair chance, and for that they lost, collectively, billions in potential revenue.
The Wii's library isn't a matter of the market speaking, it's a matter of the 3rd parties not listening. If I could have a SSF4 in SD only I'd have bought it and not cared in the least*, because it would have been on the system I wanted it to be on. And looking at the game, there's no reason it couldn't be done on the Wii at a lower resolution. In fact, until I finally went out and bought an HDMI cable it WAS at that lower resolution while I played. There's simply no excuse for that. They have had to cater to the people without HD TVs since day one and it'll be another ten years before 480 resolution is completely obsolete. They chose not to put the game on the Wii when they absolutely could have, and actual sales numbers prove that if they had even bothered to put the effort in they could have made some money.
So the only reasons not to have made their games Wii-accessible are spite and malice. Epic has malice, Capcom has spite. Okay, there is a third reason, money from Sony or MS, but it'd have to be a whole lot, since every single game these companies made had to work in 480 regardless for the people who buy a new TV once every 10-15 years (you know, THE AVERAGE). So these companies need to be told what's up. If they fully support their products and their philosophies on a Nintendo system there's an audience, and it's underserved, and a lot of that audience knows that they were ignored for petty reasons. They need to come back, accept that their product will be enjoyed on whatever system their potential audience owns, and provide the products so that they can maximize their profits.
Comapnies like Capcom need to forget that Nintendo challenged their bottom-line with the decision to use carts in the N64 and companies like Epic need to remember that once you do something high-res its a lot less work to provide a low-res version than it is to do, well, almost anything else they might consider. Because they have to provide the low-res setting anyway. Not every game would have worked on the Wii with a graphics downgrade, sure, but the truth is that most actually would have and that the extra processing power has gone to waste for those who aren't ready/able to buy a new TV.
Look at games like DMC4 and Bayonetta and try to convince yourselves they couldn't work in lower res on a system several times more powerful than PS2 (which had many, many similar games at lower res). Unless you have a very intimate knowledge of memory allocation to the point that you can literally say "this scenario is absolutely impossible without more RAM" about some point in either game, there is no excuse for them not being on the Wii other than "the devs/publishers chose not to" and that's not acceptable to me as a consumer.
*Note: I own a Wii, a 360, and a PS3. I can play any and every game released this gen at its fullest as long as it's not PC exclusive (and in a month that will change, as I have a PC coming that handles Crysis 2 at its fullest).