Henfon hit upon the key issues.
Wars don’t just suffer from poor rewards, they suffer from being utterly tedious and miserable experiences, if they’re between competitive teams. They’re not just battles, they’re 24-hour nightmares of staring at screens watching for banners…in exchange for, at best, a handful of tokens and some ranking points that most teams don’t particularly want in the first place.
After all, most teams usually move to where they want to be in the rankings, and stay around there until they feel comfortable changing leagues.
To make wars attractive to most players in the current design, you’d have to increase the rewards by orders of magnitude, and/or reduce the stress, tedium, and general unpleasantness of them by orders of magnitude.
The former can be done, but won’t be, because there’s no way PG will allow people to get that kind of resources on-demand. Especially since there’d be the potential for teams to trade wars to farm resources that way.
And the latter…realistically can’t be done, because it would require a significant reworking of how wars are designed, and PG is not in a position to dedicate the kind of time and effort it would take to do that, let alone do it right.