Yeah, and this problem will only get worse as more weapons/armors are added to the game. There has to be more accessibility to white gear. There are so many ways to achieve this, but, enchanting makes matters worse as they multiply their RNG with each other.
To also add to your problem statement. Imagine us right now and having a fully enchanted, infused, exalted T3 Greatsword. Okay, now T4 drops and a new shiny Greatsword has a moveset you like even more…
Also exalting only fixes the issue at the end of the whole chain of actions, if that makes sense. The entire process you go thru leading up to exalting is still scuffed.
The issue also lies in the fact that there are so many ways to change it that you don’t know which will lead to the best outcome. Make everything craftable, comes with it’s own problems and doesn’t adress the issue if finding the item. Disenchanting + crafting creates a loop of enchant → disenchant → enchant → disenchant which makes it way too easy. It is multiple systems that aren’t working well together. The question then becomes which is the biggest problem. I think reworking enchanting should be the starting point. And, then look at white gear availability and crafting.
True, but part of the issue is also that shooting for the 50% feels like, at least for me, shooting for 100%. And, people always want to optimize and maximize. I am one of them as it triggers me knowing the weapon can be better.
I hate how complex this issue is 
Blue’s and purple gear found in chests = vendor trash for me. Even this: Suggestion: Deconstruct, Dismantle & Disenchant Gear does not fully solve the issue of making blue/purple drops feel awesome. You just get resources/recipes from it. The sheer amount of RNG on the affixes on blue and purple gear are the issue. If they were grouped like Suggestion: Affixes grouped under Prefixes and Suffixes (Titan Quest) it makes blue/purple gear relatively more usefull as you have standardized affix groups. So the probability of finding something good increases exponentially. However, it creates new problems and doesn’t adress other issues. Like you mentioned with not each and every longsword being the same. Good luck finding the weapon/armor you want with the specific Prefix/Suffix combo you want. The odds are better, but finding the specific weapon/armor still is horrible. They could make the zones tiered zones so they always and only drop specific tier items. That could be a step into the right direction. They would also then need to review the amount of items that exist in each tier. Maybe make Finley a daily merchant or let us make requests for what tier of goods are sold at vendors, let us refresh daily or make it refresh after X hours.
Point being → it needs multiple solutions in conjunction with each other. It is a multifaceted issue.
They could also make blue/purple items drop as blank slates. So no affixes but just a workable base.
Crafting Focussed
I personally prefer crafting gear > finding gear as it adds an element of interaction. Especially since RNG of finding good gear is too random. Instead add a bucketload of depth to crafting, but make it so that the good crafting components come from chests and other drops. So we get that WOW factor from farming chests in the wild and then convert that to crafting something cool with that drop.