I’d use tonics in World vs World. My character has a sort of theme and I’d love to transform into this tonic, which matches my minipet, for all of my out-of-combat time (while roaming). The reason that I can’t is that, even though the tonic has no combat skills, I can’t pick up my usual dodge traits while transformed (Swiftness and Might on dodge). For me, the fun factor isn’t worth a significant loss of movement and power.
I think it would be cool if all non-combat tonics allowed your character to keep their traits while transformed. Some already do. For example, if you use the Arid Devourer tonic, your traits don’t work, but when you use his ability to burrow underground, suddenly all of your traits work! The toys like Sonic Tunneling Tool also allow you to keep your traits.