Have you seen how ugly with a capital U most 10mm Warmaster infantry is? The weapons and certain other parts of the models are so exaggerated in size compared to the rest of the models to the extent it looks silly and cartoony - it put me off wanting to collect and paint them personally. Virtually all of FWs 6mm model ranges are things of beauty and
far superior. Even apart from already owning so many and not wanting personally or the community to change, I prefer the good 6mm infantry to most 10mm GW infantry
6mm scale also fits nicely with FWs Aeronautica Imperialis and their future Titan Game - all good cross-over uses, while 10mm would be all new and really unnecessary and alienating for all existing players. Epic used to be popular back in the day - a supported 6mm
can do well, it's just GW attitudes and strategies that have been the problem since, not the scale. Also even if they did ever re-release epic (which I do not ever see happening unless as an FW add-on to their Titan game) no way would GW just re-release the game with bigger figures, they'd re-do the rules a lot too and in all probability screw them up (see a lot of their recent game and army rule designing).
A lot of the models are old and off-putting and could do with being updated I agree, but great things are possible at 6mm. You saying GW should release a 10mm W40k universe game is just your wish, but I don't think it is a popular or good idea.