There's no obligation, but criticising the stutus quo without supplying an alternative is just stating that things are bad. Talking about how bad things are is pointless; why not talk about what could make things _better_?

If somethings broken and you can't fix it, then you either learn how to fix it or you need to accept that it is broken and move onto something you can fix.

P.s. I really like the engineering analogy, but remember when discussing politics: other people have probably already defined the problem and come up with solutions. As a citizen, we need to choose which solution is best; or promote our own solution.