While it's true that most melee refuse to do anything but their best ws, forcing someone to do a stun ws just so you can make a crappy skillchain is stupid. Unless you're in the dunes and that stun ws isn't much worse than the only other ws they have at that level, you can almost always make a better skillchain that doesn't involve one of your DD's practically not contributing to the skillchain.
While the melee need to be willing to participate in the skillchain, at the same time if the MB difference over normal nuke is not more than the difference between the melee's strongest ws and the weak one they have to use for the skillchain, then don't do that skillchain. If you want to maximize the amount of damage done, you try to get melee that are able to do strong weaponskills together for a skillchain.
Generally the people who complain about this(not saying it's the case now, idk) are people who don't understand the skillchain chart or who don't understand how to get good exp. Rather than get 2 melee that will work well together, they just get the first 2 they see and expect them to magically unleash powerful skillchains when they often don't. Yes, the melee need to be willing to help but at the same time the party leader needs to take responsibility for inviting jobs that aren't very compatable on the skillchain chart.