Which games would you say have bested it in terms of writing/plot? I see a few but not very many really. Disco Elysium would be the first but that also stands alone in terms of quality. (That said, don't get to game much anymore so could very well have missed a lot...).
The gameplay is absolutely an important part of "should I play this now".
Plenty of games that were good when they came out aren't worth investing hours in today. Bioshock Infinite comes to mind.
If a game is relatively linear (think Last of Us, To the Moon, Alan Wake), I'm actually inclined to just watch a lets play because I can skip the "gameplay" parts.
Maybe that makes me the minority, but I don't think it invalidates the opinions of people saying PS:T was a phenomenal game even if the gameplay was nothing special
PS:T is a cRPGs not a visual novel. There is an actual game you have to play around the dialogues and this game is not particularly complex, engaging or even that fun as demonstrated by the rest of my comment lamenting the part of the game after Raven’s maze which is notorious for having lots of boring combats and less dialogue than the rest of the game.
People excuse the mechanics both because the plot was original and because they have forgotten as this part of the game is unremarkable. It still make for a less than stellar experience when you play it today.