See, for me the GM never calls for that seduction roll. The GM tells the player that the NPC is batting eyelashes, leaning in close, and maybe showing some [societally slightly suggestive region]. If the player wants something, he’ll say so, and we grab dice. If he doesn’t, no dice come up; the NPC didn’t work as a hook. I think the end result for us probably looks pretty similar: if the player bites, there’s rolling. I just effectively push less for players to bite, probably at the minor cost of some GM-instigated drama and at the minor benefit of not having to explicitly discuss whether I’m setting up an interesting situation.
Of course the players know there’s lying once Falsehood is being rolled; that’s pretty hard to miss! I just often let them know that there’s lying even without rolling, and I let their characters know as well. Some of that is personal preference against making players separate in-character and out-of-character knowledge. Not categorically, but I’d rather have the two in sync most of the time.
This also might facilitate my standard weasel NPCs who aren’t quite lying but aren’t quite honest, and who are trying to get something out of players without quite asking for it. Is it Falsehood? Persuasion? Soothing Platitudes? Often it doesn’t matter, and I just say it.
On further reflection, I really don’t feel bad about undervaluing Will by never rolling against it. I think Will gets plenty of benefit already, and I’m not affecting the prevalence of tests that might advance it.