AD vs AP Itemization : Healing from damage dealt

Anyone else feel its kind of weird how the only reliable healing ap champs have is ravenous hunter (which is not in the most frequently picked AP tree - sorcery) and requires kills to be effective, while both ad AA champs and AD casters have options to heal themselves without going back to base?

Deaths dance, botrk, gunblade, bloodthirster, scimitar...All really good items and allow you to stay around in lane/skirmishes/teamfights for a really long time if you are mana based and potentially infinitely if you are not mana based (which doesn't exist for AP champs - so they have to back for mana AND for health). While a yas or zed or riven can stay in lane forever. Teamfight/skirmish coming up? Engage, if your in a bad spot, disengage, kill a few minions or a jungle camp and your back to full health in seconds and can re-engage. Not to mention it being so damned strong during fights themselves.

I get that AP mana casters should be a more intelligent and skillshot based thing, waiting around then bursting hard, but theres much less room for error with wasted mana or bad engages. While AD casters like aatrox, riven, yas, riven, zed, lee etc don't have to worry about mana, and usually not about health either.

I don't even play AP champs but I was just remembering spellvamp ryze and Cass and realized that both in terms of general itemization and for the above mentioned issue AP casters are really forced to build and play in a certain (unforgiving) way while AD champs have many more options.