Perhaps this is stating the obvious, but...
I believe that the more powerful the amplifier and the ability for the amplifier's power supply to deliver 2x the watts as impedance is halved makes it exponentially more difficult to design and build that amplifier. Not just the ability to provide current from reserves but to provide the correct amount of current uniformly across the impedance spectrum.
If this assumption is true, then it is far more demanding on an amplifiers capabilities to drive a speaker where there are dramatic swings in impedance over the range of the speaker. So, it is far easier to build a 400 watt amplifier to sound great with a speaker that has consistent 4 ohm impedance throughout the spectrum than it is to build a 200 watt amplifier for an 8 ohm speaker that has areas that drop into the 2 ohm region even though both amplifiers could conceivably be the same.
With the Alexx V being rated at 4 ohms and dropping down to 2 ohms (which could be understated) this dictates that a 200 watt at 8 ohm amplifier needs to confidently deliver at least 800 watts at 2 ohms and potentially as much as 1600 watts at 1 ohm. This is a very demanding load for all but the finest amplifiers.
I am generally a fan of Wilson speakers and have heard many recent models sound exceptional, but anyone venturing into "Wilson Land" ought to go there with the full understanding that the selection of amplifiers will be absolutely critical if they listen at any elevated levels.
Case in point, I heard the big mono block Audio Research amps driving Alexx V and the bass was disappointing... not bad... just not "moving" but then hearing the big Boulders drive the same speaker in the same room, the bass was "Is it Live or Memorex! crushing".
I don't think it is a fair criticism of a company to design a product that has specific partnering requirements. But it does put a level of onus and encumbrance on the dealer and the purchaser to make sure they are matching compatible products as part of the sales consideration process.
I have always been skeptical of assertions of what percentage of money should be spent on which components; especially ones where the speakers take up a disproportionately large part of the budget. Anyone who is spending $100K on speakers would be foolish to not anticipating spending at least $50K on amplification (if not significantly more!). This immediately puts you into the categories of amplifiers that Jay has been exploring. I couldn't agree more that I would never expect a $200K amp to be hiding from any speaker, but I definitely could see situations where it can happen. This doesn't mean that the amplifier is less than exceptional. Everything has limitations. If this weren't the case, I'm pretty sure, this thread would have run it's course years ago! We all need to be careful to not disparage equipment that doesn't perform in a specific situation.
I have Proac speakers which are a pretty easy load to drive, in fact I have heard them sound very nice with much lower powered Audio Research amps and a friend of mine tells me he had the same speakers with a Cary tube amp and that they have sounded exceptional, but trying to drive Wilsons with them would be just futile. Jay might even say that they sound "mid-fi"... lol
To further beat this dead horse, this is why it's important to try gear in a variety of situations before being overly positive or overly negative about it!