The blue isn’t there to appear blue…it is a side effect of certain incidence angles when the light hits the coating. At optimal viewing angles it’s completely clear. You see this on the higher-end coatings ie Breitling - they are very blue at a few angles, but at their optimal viewing angle the crystal disappears completely and you do not see blue.

Just like anything else, there are imitators who use poor quality coatings to emulate the very high quality ones in more expensive brands. These cheaper ones mislead consumers into thinking that the blue is better, since you can see the blue on the expensive brands. In reality it’s usually a worse coating.

Tl:dr the blue is a side effect at certain viewing angles on some of the very high end coatings, and some companies capitalize on this by just choosing coatings with more of this effect to capitalize on the use in more expensive brands.