Why use Braid to Fluoro or mono?

I fished for many years using mono, then tried some braid and saw the benefits.
After a long time off, (not fishing due to life responsibilities) I see that now there is a trend for using braid with a fluorocarbon leader to achieve (apparently) the sensitivity of braid feel (no stretch) with fluoro "invisibility".
We can argue all of the points on each but I'm asking as an avid sportsman prefering to use the best available when reasonable but having not kept up on the transition to this system.
I fish 100% fresh water, all species from bluegills to pike/musky, use both baitcasters and spinning gear. I prefer to cast most of the time but I do troll when appropriate. I'm not a catfisher and while I would like to fish for salmon, I'm in the middle of the country where that opportunity doesn't present itself.
The best simplified explanation of this setup has been here 
Since I've recently tried this setup, having tried to educate myself of the benefits I have the following questions.
1- Is it worth the effort to use this type of setup? It seems overly complex to have to tie a "brittle' fluoro to braid knot leader that has to travel through rod eyelets weakening it with each cast
2- Since most of the freshwater fish rarely take more than a few runs most spools are filled with backer or primary line that never see's the light of day past 50 or 75 yards. Many 2500 to 3500 series spinning reels carry from 200 to 400 yards of line likewise baitcasters carry at least an extra 50 or more yards of "spare room". Would it make sense to just use fluoro on the last 50 yards? If fluoro is as superior as suggested to mono, and if (as I suggest) having to cast a knot through eyelets weakens the knots ability, then why not eliminate the damaging portion by placing the knot back where it almost never sees the eyelets.
Has anyone done a study on the knot strength of Fluoro to Braid after 100's casts through eyelets and dragged through sand and rocks? I know regular checking is important but retie-ing 20 pound slippery braid to 8 pound fluoro isn't as easy as it appears on YOUTUBE when they show you with 100 pound HiVis.
 
Any contributions, comments, suggestions, experiences appreciated.
 

I use 12-24" of flouro at the end of my braid for most freshwater applications. Uni splice, micro swivel, or Albright knot depending on application/line diameters. I don't cast the splice through the guides typically.

I have had it fail, but very likely from user error, not wetting the line enough, bad leader material or just too light of leader. I switched from a surgeons knot that was failing way too often. Good knot for mono to mono or floro, doesn’t seem to work well with braid for me at least. The amount of times that I have had uni to uni fail in comparison isn’t close. I can’t recall having it fail on heavier setups. I think many are when I size down leader when bite is slow and forget to adjust my drag to make up for it.