Personally, I'm a huge fan of the charr running animation, but having a toggle option for running on two or all four would be a good idea. It would be helpful for a few things - like jumping puzzles or similar stuff (RP too) Currently, the only option is to draw weapons or use kits.
Such ideas have been mentioned many times before, but so far nothing has changed. I guess devs are not interested or prefer to invest time/resources elsewhere.
"...But, in the historical plot, there are charrs who followed in the footsteps of intelligence..."
Standing upright as a sign of intelligence? Flame legion already demonstrated "higher intellect" before...
Look at Iron Legion engineers - they run all fours and at the same time they are the ones who invent complex machinery, weapons, or other steampunk-style technological marvels.
Iron Legion metallurgic knowledge is also pretty impressive - even asuran scientists are visiting BC to have a chance to study them - this alone suggests that charr are pretty smart.
They don't have to stand upright, cast firebolts, and terrorize others with their false gods.
The upright pose was always more of a superiority complex.
A lot of such lore details can be learned from various NPCs in BC.
Running on all fours is something natural for all charr. Running on two legs or on all four has nothing to do with "intelligence".