Nether quartz should stay as it is now, with the sole exception of the aesthetic blocks being attached to this new plain quartz item instead. Nether quartz should be for functionally-important stuff like beacons and redstone.
Thousands of blocks? Here is a map of one of my worlds, showing all dimensions:
Here are my statistics - I mined over 10,000 quartz ore, mainly to get the XP I needed to enchant my gear, but I also use it to build my main base - I didn't even use Fortune (2.2x multiplier):
I wouldn't call that going far at all; even the Overworld is only slightly larger than a single level 4 map, which is rather small by today's standards, what with 1.7+ world generation (the world shown here is a modded 1.6.4 world where biomes are more or less random, like in vanilla 1.6.4; strongholds are also much closer (640 vs 1400 blocks minimum) and there are no super-rare structures that need special maps to even hope to find them) and newer, faster transportation methods. I also mined only 4% of all the quartz originally present (a lower percentage than what I average from Overworld caves for most ores and similar to diamond, if biased by untouched chunks around the edges of the explored area) - there is close to a quarter-million ore remaining - and ores are more common in newer versions (1.8 added 1 to the size of all veins, increasing their size by around 20%; I measured a concentration of about 0.6% relative to Netherrack but it is likely closer to 0.7% since then, as also seen with iron (compare to the old chart from 2013), which the Wiki states is similar in abundance).
I'd also say the same thing about other ores - I regularly mine over 3,000 ores per play session while caving (in the Overworld), while covering an area of about 100 chunks (160x160 blocks), and there is relatively much more area exposed in the Nether (quartz is about as concentrated as iron, 0.7% of blocks, which means an average of one ore every 143 blocks, including the surface area, and each exposed ore is likely to be part of a vein of multiple blocks; the rate at which I can mine quartz is comparable to the rate for all Overworld ores).
1.) Some materials are intended to be more special than others. Coal is abundant, diamonds are rare. Cobblestone is abundant, diorite much less so. If every material was easily available in quantity, it would greatly diminish the uniqueness of those rarer commodities and greatly diminish the joy of acquiring them, ie, diminish the quality of the game.
2.) Dropping quartz from sand would not be a very efficient way of amassing quartz in quantity.
3.) It would actually make more sense for granite to drop quartz, rather than from sand. I'll leave it to you to research the basic geology of the materials to understand why.
4.) If you really must have an alternate source of quartz, Masons offer it as a trade item.............