I realize that wards are very important and since I mostly play support I am usually the one that gets wards, but if I don't get as many wards because I am playing some other role I realize that no one else gets wards. Is there some way to convince other people of their importance to the game?
In a game to game basis, there really isn't much you can do to get your team to buy wards other then just asking and hoping, but when you get to the higher elo games people take it seriously and will also be buying wards. In lower elo games/unranked people don't take it as seriously/have the same skill level as high elo games and either don't buy wards or take offence to someone calling them out on it, which just makes the team do worse. If you're the only one buying wards, just do your best to get wards around dragon (although this is less important in unranked/low elo play), baron, and your lane.
I don´t aske them to get them, I know they are an advantage for and my team and even if I am playing a carry champ always try to get at least 1 ward.
There was a game where I was Nunu support and always warding saving the life of my team mates preventing ganks, they noticed this, and proceed to ward the complete enemy jungle as team, that was hilarious, we destroyed them in their jungle and won the game.
Just keep doing the right things right, they will learn. (Someday)