Since the LG is a web enabled player, you will be able to update it as easily as the PS3. The difference being that when the LG is about 1-2yrs old, they will definitely stop releasing updates for it vs. the PS3 which will receive updates for years to come. Because the PS3 is a much more powerful unit, it has a lot of other capabilities that can be added to it due to the hardware. Things like 3D capability will be a firmware update for the PS3. They are going to release a kit that allows you to use the PS3 as a DVR, something you definitely won't be able to do with a stand alone player.
What types of games do you play? There are a lot of free and/or cheap games available on the PS3 online (PSN) that are quite fun, so it isn't all about buying full blown games all the time. It already has Netflix and the DVD upscaling is pretty good. I almost agree with the part about gaming, and was going to say something similar, but if you are going to game once or twice a year, it probably isn't worth it. If you think you will play on a regular basis, then as mentioned before even by you, it is a no brainer. I game and I pretty much use the PS3 just for gaming.