That's something I also noticed during my map retexture undertakings.
Altering the sun height (most BF maps have an almost midday sun) and an increase in shadow "darkening" can enhance the immersion vastly by simple means. I usually try to combine moving the sun closer to the horizon and thus having better object lightmaps with better lighting during texturing of the terrain itself (Editor 42: Ambient 0.2, Sun 0.8) which supports that immersion greatly.
How did you make BF generate 512x512 OLM? That's something I think would really increase the quality a lot, as with 256x256 you easily can spot the shadow "pixels"
. And I strongly doubt it would mean a high perfomance impact on nowadays computer rigs, right?
Oh, and is there a way to force BF to generate higher quality terrain lightmaps too? I never quite figured that procedure out. Even if you set it to "perfect" in BC42, the rendered shadows are chubby and pixelated (best example: render shadows for a single palm...) which kinda sucks, especially if you use HD terrain texturing...
And last but not least, is it possible to enhance the "real time" shadow rendering quality of BF? I mean the dynamic shadows e.g. soldiers and vehicles cast on the ground? I once looked, but never found a proper parameter which got that working...