Impossibility of early vision makes it too risky to push early advantages
With how long trinket wards last versus their recharge time, visibility of control wards, and inability to purchase anything else other than sightstone (which would entirely negate any advantage you'd have in a solo lane) it's impossible to have adequate vision in the early stages of the game.
With how powerful junglers are now, I think this is really the true reason behind it. You can't ward to protect yourself. If you use your trinket ward, it's really not hard for your lane opponent to ping it. Jungler comes 61 seconds later and you're done for. If you use a control ward, you're handing some of your gold to the enemy team for free as they'll no doubt see it when they come to gank. Sure, it MIGHT save you once, but he's there now and knows you don't have vision. Pretty easy for him to stick around, or go another route. And I say might because it may not. You can't ward deep enough with a control ward. The river bush? Too late by the time you see him if you're trying to harass under tower. The dragon/baron bushes? They can come out higher from their jungle without being seen by it (especially if using a blast plant).
It's impossible to ward adequately in the early game against anyone that's paying attention.
So how do we solve this? A) Add a mastery that increases ward duration or reduces ward recharge time. B) Allow players to "refresh" a ward by channeling on it for 6 seconds. If you're even in lane your opponent can easily interrupt the channel by damaging you. Only when you're in a position to push an advantage can you do this, and in that case you have to give up harass in order to keep your wards up. Trade offs. C) Reintroduce stealth wards. With more options than ever to deal with or avoid vision, stealth wards probably wouldn't be OP anymore (IIRC, they were removed because at high levels of play junglers couldn't get any pressure since everyone was constantly warded).
Any other suggestions.