There's a time and a place for everything. Including polyester suits. The really good polyester fabrics look a whole lot like really fine wool weaves, so let's recognize that right off the bat. The really bad ones will be fairly obvious to anyone with experience in menswear -- and the rest will be fully oblivious, so make what you will of that.

The truth is, I imagine, that the great majority of wool suits aren't worn near enough to justify the great sacrifice from the animals and people who made them or made them possible. Cleary, the guy who is going to wear the suit every week should invest in a proper fabric (and construction), and equally so, the guy who needs to wear it once but needs to wear it to a serious occasion where people will notice the difference also needs to invest in a serious fabric.

For the rest of it, there's no reason synthetic shouldn't be viewed as a legitimate option.