Making Vehicle Combat relevant

I always wondered why in D2 vehicle combat feels like a side note when it was one of the main reasons why the Halo games became so popular. I get that these two games are very different from each other but there could be done some improvements that doesn't make them feel like you're wasting time because you don't gain any exp. for using their canons. So, my idea would be that we're able to gain exp. to upgrade our weapons for actually using their canons. It could be like gaining exp. for power weapons for using heavy canons and for energy weapons in using light canons, or the exp. could be also split and give all three weapon types exp. at the same time. However it would be done it would make vehicle combat feel organic and fun in the game and players wouldn't have to worry about losing exp. while using them, and that would also allow to create some three or four player vehicles, like the Warthog or the Spectre from Halo. I mean, they could even explain how that works in the lore with light or darkness. Maybe our Ghost is using its light to transfer our weapon abilities to the vehicle canons, so that they can also have them while we're controlling them. The same things could be done for Space Battles, maybe in future.