I agree they're doing something newer, but newer isn't always better.

Antiques, for example are deemed far more valuable than Ikea furniture.

But I just wanted to run with the metaphor, because I'm bored and feel like an exercise in the futile...

Ikea furniture kept in mint condition would also be considered antique given enough time. Think of tins of food from yesteryear or other consumables whose values now are far greater than they would originally have been, far above the rate of inflation. They reflect a era and the artifacts that existed in that time.

Most people have a negative association of the quality of Ikea furniture, for example many tradesmen will explicitly point out that they charge extras to install kitchens from Ikea as there are usually parts missing or have been built incorrectly meaning the task will end up taking a lot longer, costing the tradesman more money. If you owned current Ikea furniture in mint condition 100 years from now when most other examples broke within a year or got thrown out when their owners moved house, they'd probably be quite a rarity.

Conversely, the furniture is still very popular, so you'd still be quite likely to get more of them existing than any of their less common counterparts. This rarity will reflect on the price.

I assume the original antique we're talking about has been designed by some reputable craftsman as opposed to just relying on age and rarity to bolster its price. In this case, we're equating the prog rock pioneers that inspired The Mars Volta as high quality craftsmen of their time, creating fine art. According to this measure, we can't draw a parallel directly to The Mars Volta and an antique, neither could we do so with Of Montreal. This is because they're not the original artists, merely modern artists heavily inspired by others. Instead we equate them to some sort of artist heavily inspired by artists of yesteryear, in particular a scene or genre that was once fashionable. The originality isn't there, but their quality of their art is in the efforts of remodelling the source materials to collage something of their own.

The Battles and Ikea comparison I find even harder to swallow. Ikea furniture is available worldwide, and is generally marketed as a cheap yet stylish solution. It's not everyone's favourite choice, but the brand has become a household name, with their examples found in numerous locations. Property landlords often buy Ikea furniture en mass to fill accomodation they rent out for the reasons mentioned previously. To equate that to Battles would be like saying Battles write music suitable for television advertising. Paletable and inoffensive enough to make an immediate impact yet easily associated with a particular mood. Can you imagine watching Match Of The Day whilst Ddiamond plays in the background?

There are many examples of expensive antiques that I would never want in my home as despite their high label price, they may look hideous in my opinion. However, if I were given one, I'd be more than happy to take it in order to resell it and make some money. In a converse way, Ikea furniture is relatively cheap and its popularity is predominantly for that reason. For those reasons, I'd argue that the basis of your comparison is about which one has the greater financial worth since, as with music, a choice in furniture is opinion. I personally don't think either The Mars Volta or Battles are particularly marketable with the music they create and collectively talented enough probably make a lot more money simply by changing the style of music they create to something more universally paletable. Again I can't see how this would make the comparison hold.

music that's 'technically' good but unlistenably poor.