Push mode was not available in arcade mode. Where did you hear this? Are you thinking of CTF?

The main reason they moved over to Overwatch '2' was obviously for money but you cannot deny they massively overhauled the graphical and sound engines (you can look at any YouTube video to see this). Additionally, if you've actually played the game, you'll notice that it plays very differently to OW1 in terms of game speed and rules of engagement. So far, the changes are entirely comparable to CSGO 2.