I don't see why not. As Calibre has pointed out, RM is just as capable of producing what you call 'retail-level' games. It may not look like FFXII, but there are several commercial games out there with specs that RM is more than capable of imitating, if not outdo entirely. Again, using RM is a choice made by you, the developer, because it caters to exactly what you need. If you wanted something along the ranks of Half Life or Grand Theft Auto IV, then yes, RM may not be enough and you'd be a fool to attempt as much on it. But that's not to say RM is inferior.
Success/Profit is in marketing. Naturally, one has to know one's product to sell it properly. In RM's case, a game file is normally no larger than 200MB. Actually, that's already very large in comparison to most currently in distribution, but let's hypothesize that an all-custom game with a completely original and extensive musical score may reach such a size. By modern standards, that's chump change in disk memory, perfect for online distribution and placing in your portable hard drives to play with when goofing off at work or in class.
Going 'retail-level' where you actually distribute your game in printed copies is impractical and a lot more expensive than distributing online. You'll probably need to place a bigger price tag on your game to cover these expenses. For what? Better exposure? Probably not. When you're at a Target or Best Buy looking at your game's package sitting between a World of Warcraft and a Modern Warfare 2- no, make that between Septerra Core and Dune 2 (They're either old or obscure, but will probably look way better than your game anyway) you have better chances of selling if you'd placed your game in the bargain bin, in which case you'd probably lose more money than you made in a sale.
In contrast, let's try opening up Big Fish Games' online catalog. Collapse. Zuma. Plants vs Zombies. Text Twist. Next to these things, an RPG would look spectacular. With the exposure these games get on major websites as well (I believe Yahoo! is partnered with Big Fish), that's a lot of eyes and potential sales for you. And it won't be as expensive as distributing printed copies.
What seems to be holding everyone down here is they're setting their sights too high. First, this is a question of would we buy an RM-made game, not a question of whether or not it would be competitive against other commercial games. Second, you can't compare how an RM-made game will fare in comparison to say, Final Fantasy XIII or even Lunar:SS because they're on entirely different platforms. You can't really compare an RM-made game to the likes of Fallout 3 or Half Life either because the genres are different. There are actually very little English JRPGs commercially distributed for the PC, so that's actually a fresh market you could tap into where you may reap huge rewards in. As Calibre has also pointed out, there's a niche market for those who prefer playing old school- I myself prefer my games in 2D, so if the TS asked if anyone would buy an RM game to see if he would make any profit at all in selling, then yes, he probably would. How much is another discussion entirely.