This stuff has been going on for awhile. I suspect in the case of Forza 6 in 900p they could run more AA and AS. With cars specifically, you get a ton of jaggies with a mostly straight car profile leaning into a turn or whatever. It wasn't noticeable at first but after playing awhile and noticing it... its everywhere. The markings on the track, the horizon, the car profile, the border between the windows and the paint, all very jagged and in dire need of more AA/AS.
...
That is a screenshot of Forza 4. I personally would prefer less textures and resolution and more filtering, in a racing game at least. THERE ARE LESS JAGGIES ON XBOX 360. That is absurdly unacceptable considering the hardware differences.
Yes its darker, and the resolution is lower, but my god are those jaggies bad in Forza 6.
Well, here's the thing. What leaves you with more jaggies on a 1080p TV, 900p with more AA or 1080p with less AA.
I think the end result would be pretty close looking. 900p isn't enough native pixels to fill a 1080p display so despite there being more AA applied you are still going to get edges stretched and a whole lot more temporal aliasing as a side effect. At 1080p the edges won't be stretched and temporal aliasing should be lessened but you can't run as heavy of an AA algorithm. Each case presents a trade off.
The problem essentially is we still have an Xbox that is underpowered for the native resolution of our TV's.
This "situation" became apparent to me during the 360 generation. I'll never forget the day I got my first HDTV and Call of Duty looked *worse* on it than on my Standard Def TV due to the low 1024x600 rendering resolution being less than the native res of the panel. So despite the game having 4x MSAA, it was a total blur/jaggy fest on the HDTV while it actually looked cleaner on my old SDTV due to the free downsampling AA you get running from a higher res source to a lower res display.
And now a generation later the new console still can't properly fill the display on a 1080p TV. It's either 1080p with bare/nonexistant AA or 720p/900p with some AA.
Hopefully the next Xbox will be able to really handle 1080p but by then will 4k TV's be commonplace? So the PS5/Xbox2 will try to bump up resolution again and we will suffer the same lack of AA, bad LOD bag of tricks to keep things running.
Consoles are facing a losing battle trying to keep up with display tech which is why I am not upgrading beyond 1080p on my displays for the foreseeable future.
How crappy will the games look on a 4k TV when somebody is watching an 4k Ultra HD Blu Ray and then switch over to the Xbox game running at 720p/900p.