It depends on what you want from the game.
I liked it because it allowed for match types not allowed in the original release that in all likelihood will never be added in officially. The UFC octagon knockoff arena (the dodecahedron I believe) allows for KO/sub only matches but is limited to one on one encounters; now you can put in any kind of tag match or even an 8 wrestler free for all of mayhem. There could be a royal rumble type battle royal, but limited to only eight competitors; now you can have thirty or three hundred.
There were also other significant quality of life updates if you are someone who would sim a good deal. You could disable low damage subs from actually tapping someone out at high damage (basically you will never have an epic 30 minute match end via a headlock). I believe there were ways to pick who would win the match via this as well if you were into efeds and that was something that would help.
Beyond that sorting and deleting edits is a massive pain in the original game, mods don’t make it perfect but they help. You can turn on lifebars if you want. You can change the camera angles if you really want to (this would only help those really into simming as it is virtually unplayable in real time). They did at like a hundred or so moves into the game, they also allowed for custom parts to be added to appearances.
So… yeah, that is a lot of various things and that isn’t exhaustive (although it likely covers the big ones). The update adds in 40 or so official New japan wrestlers, a visual novel story mode and a bunch of new moves if you pay $20 for the DLC. If you don’t, the update adds in 9 moves, a new menu and that’s pretty much it. Oh yeah, the DLC makes it so that the game must have an online connection in order to be playable.
Fortunately(?) for you, if you buy it now on the PC you don’t even have the option of worrying about the mods as you will be on the 2.0 version, so I’d just focus on what you’d have rather than what you theoretically lost. The base game is still rather good! I bought it for that and was very satisfied.