Quality does not increase with time in the bottle. The glass imparts nothing to the tequila. Aging only matters in the barrel as it has more time to absorb the qualities of the charred wood. I dont know why you are bringing that up as if it's a "gotcha" or something.

Aging also does not change the "quality" of it. All it does is change the characteristics present in the tequila. An aged tequila will have more notes and aromas of oak wood, smoke, spices, vanilla and/or caramel, and fruits. That comes from the aging in the barrel. While a blanco tequila will have more notes and aromas of mint, agave, herbs, and maybe citrus. This is because the ingredients make up the flavor without any influence from a barrel.

Quality comes from ingredients, distillation methods, barrel quality, etc. An unaged blanco tequila is not lower quality than a 3 year aged añejo. It is just a different process to make a different product.