PVP is only NOW a side game. At the height of PVP it was definitely on par with PVE.
It was a distinct play-style that was so important they changed how classes played in PVE to balance PVP (looking at you TOT in MOP).
If you think it’s a side game because it has less content, I would argue that it’s inherently more fun to beat the crap out of another person who has some level of reaction rather than a static ai who is so predictable addons can tell you minutes in advance what they’re going to do.
The reason they make PVE content more frequently than PVP content is because no one battleground or arena you ever go into will be the same, keeping players interested for longer periods of time.
TLDR bring back my PVP gear that is actually better in PVP than PVE gear so I can steamroll this noob who thinks the hardest part about this game is “not standing in fire”