I think the Hull Down as it is right now just has no place in this game. Why would someone want to get a tank to sit around on 1 spot with it? You can get HMGs and PaKs for that. And if it would get some serious buffs it would probably become OP.
I think it should get reworked so it gives different bonusses to different tanks somehow.
Hull Down is quite amazing for Panthers when you have to defend because it gives them 62,5 range and 1280 HP (1422 if you have a Command PzIV nearby). Brummbar is also very good at defending a victory point from Hull Down because it has great gun traverse with 44 range.
For most other tanks it's quite useless though.