I flew HKG-BKK-CDG r/t on TG in Y a couple of months ago and encountered a similar scenario at CDG. Full flight (or at least in Y), crowded gate area and uncaring gate staff. I was traveling with a friend, and both of us are *G, but we didn't get upgraded.
You're right about TG's inferior C seats. However, I have to say their Y product is not bad. I actually prefer their Y seats, as they are relatively comfortable and seem to recline more than those of their competitors, even compared to UA's E+ seats.
TG also consistently offers better VLML/VGML (vegetarian) meals in Y. (Strangely, the only time I had a bad VLML meal on TG was in first class.)
Their service on long haul is OK: worse than SQ, on par with CX, and much better than UA.
The worse thing about their Y class is the paper towels in the Y lavatories! They are so thin and filmsy and disintegrate with a touch of moisture, making the simple act of hand washing a most unpleasant experience.