That's how the always looked like. We haven't change the textures themselves with this update, we only changed the way the same textures are displayed, using native P3D4 SDK instead of the FSX SDK, which will prevent flickering.
You must understand that KIAH it's a scenery that has been released in a difficult time, when nobody could foresee a 64 bit simulator, and we were unfairly accused to cause OOM crashes with our previous scenery ( CYVR ), when in fact the real problem was that users were trying to use it with too many addons at the time (OrbX PNW, Vancouver+, PMDG, etc.) and FSX could only work with so much stuff at once, before OOM-ing.
So, even if OOMs weren't "caused" by CYVR, we tried to do the next scenery (KIAH), as light as possible and as trouble-free as possible. Which worked, since KIAH is BY FAR the scenery that requires less support, since it just works. But the downside of it, is that some people see it as a "bland" scenery.
I guess KIAH could benefit for a full remake for 64 bit, like we are doing for O'Hare but, it's likely this will have to wait, since JFK and KLAX will likely be the first in line to be remade (and together, it will take a couple of years), after KORD.