Don't people remember for how long we got cross-gen games because publishers still didn't feel comfortable about leaving the PS3/X360, even after eight years? What makes you think that publishers and developers would be willing to make new versions of their games every three years for consoles that would sell to few Xbox fans?
To answer your question, if Microsoft wants to be hated by consumers and developers, yes, it makes sense.

An upgradeable console would be one thing, to actually buy a NEW console every three years would seem a bit silly.

I see $500 is a good for the console market. Microsoft could build a faster apu with more memory for $350 and sell the console for $400. 

The point is to not selling the console at a loss, but at a profit.

Some gamers will get upset that there is a more powerful console out, they will just have to upgrade to have the latest.

No thanks. Personally, I don't really care if it's not the most up to date as far as graphics, I just want good games. It already takes about 2-3 or even longer for a AAA game to release. A new console every 3 years would take away from development. 5 years minimum for a console cycle.

Considering Sony has the lead by a lot already, dividing the XBox userbase every three years would be a terrible move. People would just buy the console they know can last 10+ years.

Developers just have to make the game once just like on PC, the same game will just look better on the newer console.

Developers will build there games with forward compatibility in mind as phil mentioned.

I'm sure even the 2 hardcore Xbox One fans out there won't be on board.

It will be more than $500 or not as much as an upgrade as you would like.

The R&D costs, factory retooling costs, marketing costs, stocking extra sku's, all need to be divided over much lower sales expectations of this new device.
Just selling the console at a little bit of profit is not enough. MS is not in it for a zero sum game, plus this new console also needs to generate cash to start developing the next console.

The general public will look at a $500 dollar XBox One S vs a $300 ps4. Now DF can shout all they want that 1080p at locked 30 fps with sharper shadows is much better than 1080p with frame rate dips and occasional screen tearing, yet the difference will be too small to justify paying $200 extra for the same games. Developers are not going to make a generational leap in lighting for this new upgraded hardware. It takes them 3 years to get comfortable with new hardware as it is.

It does not make sense. Current console price/power ratio is factored on the fixed hardware being sold for upto 10 years. Either you raise the price significantly or lower the power significantly. Both will make it a lot less desirable next to a competitor that adheres to the 7-8 year cycle and 10 year support.

The way I see it is PS2 (2001 most places) vs Dreamcast (1999) + Xbox (2002). Sure you can launch earlier but if you do not have proven support and good games then it won't work. Sure you can launch after and have stronger hardware but people are already supporting the popular console at the time. The only difference is MS would own both consoles and make it completely BC. So instead of the 160m PS2 vs 8m DC+ 24m XBOX, it would be like 120m PS vs 25m XBOX+ 25m XBOX.

It goes without saying that a new PS console will probably be popular unless Sony messes up worse then the PS3.

I'll be damned if it happened.