Complaining after the fact does not get you ganks & makes you look like a whiner. Asking for ganks (hopefully) gets you ganks.
And don't use "it should be obvious" as an excuse to complain instead of asking first. Here's 3 reasons a jungler might not have ganked your lane:
1. The jungler overlooked it; he has to keep track of the entire map, and accidently neglecting a lane is easy.
2. The jungler decided ganking your lane would make a bad situation worse: if your enemy's fed, they could easily kill 2-3 of you during a failed gank and become even more fed.
3. Your lane was constantly overpushed when the jungler was nearby and he didn't have a good opening for a gank.
If you straight-up ask him for a gank bot, he either has to A)confirm he'll try to gank bot, B)explain why he isn't ganking bot, or C)ignore you completely and take flak for not communicating. Let me put it this way: I can't think of any situation where complaining about a lack of ganks gets you a better response than asking for one.