I thought movement speed capped at 25% (so if you had boots with 12% you would only get paragon level to 13%), but I see builds where people max 25% on paragon, put move speed on boots and even more on rings. Did it change or did I never understand it correctly to begin with? Thanks.
One reason why people put max paragon in MS might be because it's so damn annoying to check "how much do I need for max MS". Also, if you switch specs using the armory and put on different boots, paragon doesn't change - so you need to swap 26 points from main stat into MS when switching from no MS boots to MS boots.
If you're at 15000 main stat, 26 more paragon points make so little difference (less than one percent damage), but missing 12% MS can be really huge, so many people don't care, max MS, and just never look at it again.