"We need smokes."

Maybe we do. Maybe we don't. But if you feel like we do, you should consider playing those agents yourself.

"I don't play those agents. I'm a [agent that doesn't smoke] main."

Telling someone to fulfill a particular role on your team is a poor way to make up for your own lack of versatility. At best, it's bad etiquette. At worst, you are conveying to your team that you are willing to dictate how your team should function (backseat gaming) while refusing to adapt your own playstyle to various team compositions.

Consider the following:

• If you firmly believe we need smokes to win, then you (should) know how to use smokes effectively.
• If you know how to use smokes effectively, then you are likely more qualified to smoke than a player who doesn't immediately select an agent with smokes.

I'm not going to get into the debate on the importance of smokes in competitive play, but if you're more comfortable executing plays that involve any specific utility (smokes, flashes, etc.), you might as well be the one who provides that utility on your team. By insisting that someone else fulfill a role to complement your desired playstyle, you are essentially asking another player to solve a problem that may only exist for you.

TL;DR

If you're going to ask for smokes, be willing to provide them yourself.