I have no nostalgia for Mass Effect. I started to play ME1 before the Legendary Edition was announced. The game clearly showed its age in the gameplay department. Legendary Edition smooths over some of those in ME1 (I can't speak to the changes in ME2 or ME3 having not played those previously) but the age still shows through a lot.
But the story and choice & consequence are clearly stronger than almost any game published today. It carries the series. It helps you look over the tedious planet scanning/searching for resources or the long and redundant hallways that aren't needed with today's technology. These are remasters and not remakes so those older design choices hold it back. The gunplay doesn't measure up to today's standards either.
However, the weight of the story and the character development and the impact of your choices through each game still make it a very enjoyable game. I think though, nostalgia has helped boost ratings vs the overall quality of gameplay when compared to the best of AAA games released today.