Thing is, we all agree thet no matter what it won't be more realistic than real life, lol.. But put it this way, having anything weather related behave the same way every time is not any more realistic than having generated weather with sligly less realistic characteristics.
Yes, ridgelift can be as simple as wind blows on hill and gives you 2m/s of climb, but due to the shape of hills they react differently to wind speeds and angles. I have never seen a single ridge that is straight like a knife, and so as wind direction changes, different parts of the ridge generate lift.
There are a ton of factors that come into play even when it's just ridge lift we are talking about, and i could record you my flight data from my gps every time i go on the ridge, but they will all be very different.
The whole "reason" people do gliding is the challenge to stay in the air, and this is all based upon using your experience reading the weather to figure out where to place your bets on the best thermals/use keep track of wind directions at altitudes to find ridgelift and wavelift. If this was all static i would give the game a try a few times, and then go back to condor. Condor isn't at all perfect, but with no other competitor and featuring decent/ok generated weather that changes all the time it's still great.
If i could stay in the same spots all day long, then what would be the challenge of gliding? in real life thermals do tend to happen at some known areas, but the can literally appear anywhere.. (well, you might have a hard time above water or other special areas...)
What im trying to say is that i'd rather take a bad generated weather over a static, but possibly more realistic weather based on statistics gathered from the area because it will give diversity and acually realism, becuase weather is never static.
EDIT:
Ok, drop the thermal stuff for now. Point is, good luck getting all the data for every inch of the ridges rather than doing a simulation of it based on elevation data. And you'd still be really restricted to where you can fly.. which is counterproductive for an engine like outerra that builds upon having the whole world for you to explore..