At least twice as many trash encounters as both BG games combined.
Sounds to me like you have your nostalgia goggles on.
No. I have replayed both BG games more recently than I played DA. I don't like BG1 overly much and have stated so on multiple occasions, because of generally lame encounter design and a bland setting compared to BG2. But even my not-so-well-liked BG1 has much better encounter design than DA.
Comparing body counts of the games isn't how you do a proper comparison. A game may throw 50 mobs at you but there are 10 different varieties of mobs, or a game may throw 40 mobs at you but every mob is the same. Which one has more trash mobs? Answer: the game with 40 mobs, even though the total number is lower, there is less variety compared to the other game, which makes the combat against these mobs more repetitive and therefore a rote exercise in performing the exact same tactical movements again and again.
The BG series has a huge variety of different enemies, especially BG2. You have plenty of mob fights in both games, but many of these are challenging to get through. Not every mob is a trash mob. Copypasted and trivial to beat mobs are trash mobs. Due to variety and challenge, the mobs of the BG series are not as trash mobby as the mobs of Dragon Age.
Trash mobs in BG1 could consist of xvarts, goblins, bandits, orcs, gnolls, wolves. In BG2... uh... I don't actually remember BG2 having any trash mobs as such, since its level design is focused on unique hand-placed encounters with a huge enemy variety. Even when you encounter trashier enemies they tend to be arranged in a way that makes them interesting (like the orcs shooting at you from behind a wall at the start of Firkraag's dungeon: a generic enemy, but placed in a way that makes the encounter intersting, therefore not trash).
Meanwhile in DA I remember slaying my way through the exact same hurlock encounter dozens of times. A single dungeon would consist of half a dozen rooms on each level, and each room would contain the exact same copypasted hurlock encounter over and over again. In the werewolf forest, it was the exact same werewolf encounter over and over again in each room. There was some variation throughout the game, but no variation within levels themselves. If you went through a hurlock-themed dungeon (Deep Roads, for example) hurlock encounters were all you ever got.
Part of what makes trash encounters so trash is also their closeness to each other. If a game has 20 goblin mobs but each of these has half a dozen other fights in between, it won't feel as trash mobby as when these 20 goblin mobs appear right after each other. Dragon Age would often drop the same copypasted encounter on you a dozen times in the same dungeon.
This is why Dragon Age felt so tedious to me. Copypasted encounters that weren't very challenging chained next to each other so you'd fight the same encounter two dozen times in a row with no variety in between. Terrible.