SPG's, plural. That would be the first question to address, cost-wise, reliability-wise, etc.
The second point is that a tech diver is supposed to plan his dive, dive his plan (not that this not part of the recreational mantra, but practically?), so gauge checking, while useful, is to some extent unnecessary or infrequent, as long as the dive goes as planned.
Third, there is much info reflected on the computer already, specially for rebreathers, so crowding the display with extra info which is not that critical, would be counterproductive.
And as mentioned, these things would have to withstand pretty harsh conditions, not just depth...
In principle, an exact knowledge of gas consumption would sound like a good piece of info to fine tune deco calculations. However, inferring gas inhaled from gas consumed is not really possible, as you could vent your loop, or flush it (speaking rebreather here), etc. Knowledge of the gas content is what matters most, and you do enter that manually (and for a rebreather, pO2 is read continuously in some configs, or assumed to be maintained by the divers in others).
So bottom line, there are very few advantages and quite a few drawbacks of adding this to a tech computer. At least, that's what I could imagine to be some of the reasons for SW not following in the tracks of Liquivision... But who knows? Never say never!
Disclaimer: I am truly novice in tech diving, but at least I do not dream of having all my tanks wirelessly connected to my Predator anymore