League of Legends (LoL) Question: Why no one plays Heimerdinger ?

He is a good pusher but his main problems are that he can't do proper initiative attacks and he's very squishy and immobile.

He does well when enemies are baited into his turrets but his e is too unreliant, his w drops all on bruisers in teamfights, his turrets can't move along with the teamfights, and he has no other reliable sorts of damage besides his w. He can't initiate a fight well as well and can hardly touch the enemy carries unless in skirmishes early on.

He's getting a rework don't worry.

Heimer is barely played due to his difficulty and misunderstanding. Most people believe its all about the turrets. Then they are unable to do damage cause they have only maxed one skill. He is really strong if you have a team who can communicate well though.

Heimerdinger became famous because of me

I used to play as Heimer all the time, but he has been nerfed horribly. His rockets have a 10 second cooldown, his turrets now take almost 30 seconds to activate per turret, and his stun is slower, longer cooldown, and his ult has become all but useless because of these nerfs. The rockets can't be spammed anymore because of the cooldown, his turrets are easier to destroy and are longer to resurrect, his stun can't guarantee a kill because of the nerfs that end up stacking against heimer. Other champions, other less useful champions are now OP against heimer. Last game I saw a heimer, I was picking on him with Swain, a champion I used to pick on as heimer.

The Dinger's amazing pushing ability is always preyed upon by the enemy jungler, especially since dinger doesnt have any mobility. He excels in forcing a fight around baron or dragon, especially if it is the enemy team attempting it, b/c he can bait the enemy into turret-filled brush or block off escape routes.
Jungledinger is hella op, he barely takes any dmg, and can counter jungle surprisingly well if he strategically sets his turrets similar to Shaco when he sets his boxes in places guaranteeing his enemy wont escape.
The Dinger's pushing capabilities can be abused to bait a gank from the enemy jungle, allowing your jungle to set up a strong countergank beforehand. With help from teleport or lvl 5 boots, heimer can actively apply pressure on ALL THREE LANES. Just set one turret in each lane and yourself mid. I hope riot adds cc to one of dinger's ability. A slow on his rockets would improve his ability to avoid ganks, and would make the dinger a scary ganker :). Plus his walking animation is dumb af.

Because he pushes his lane to smellerine and have no reliable gap closer to escape ganks. That is a very dangerous combination.

He can be good though, just very situational. You can counter a lot of roamers and gankers, such as Evelynn, by forcing her to stay in lane to clear waves at her turret. This can be easily achieved with other mids as well (Lux and Orianna both pretty much oneshot minion waves...), so it's not really that great.

His poke is also very effective for shutting down some melee champs, most notably mordekaiser, since you can basically prevent his passive, and outpush him. Some melee champs (Kassadin, Katarina) owns Heimer because they can get in and out of range quickly, so they can basically avoid poke and chunk back effectively.

My advice is to use heimer as a counterpick.

I've had a lot of good games mid as Heimer thanks to his turrets it's easy keep a team fight under control with them. Yes he is under used since there are better used APC's , but a skilled player who knows how to take advantage of some of the new-er players not knowing how to counter Heimer he can be used pretty effectively. I will agree with the blind and stun being unreliable, but only outside of him using his ult. Most of the end game you will be relying on their team to be baited into the turrets yes, but if you deploy them in the middle of a big team fight rather than pre-placing them you can do some good with him. His rockets I do feel need better ratios or some sort of effect behind them because most of the other APC's have a 2nd effect on top of damage behind an ability unlike Heimers'.

heimer can do well, but atm his range sucks in comparison to other apc's, his stuns aoe range is basically nonexistent and the blind barely helps, his ult is basically useless since basically everything on ult should be moved to his skills/passive. Early and mid he's pretty good but later on he sucks **** because Orianna or Karthus etc do everything better then he does while either being less immobile or bringing other things to the table that heimer doesn't have. You can still play him well, but he takes to much skill for to little reward.