I will start this by saying I have 3 master angler characters and have 20 fish to go on my 4th. My friend and i both have these stats as we love to fish in eso. We also play on Xbox so we're slightly behind the guy with 12 on pc!
With that said, housing has ruined fishing.
Here's why.
When fishing before housing; the odds were already awful. This is why Master Angler is always argued to be the hardest achievement. Sure, it's not beating maw on hardmode, but it shows true dedication. It takes FOREVER to catch all the fish required and takes a bit of knowledge to know what works best to accomplish this. Dedication is an understatement.
When fishing before, each water type contains two specific fish and a specialty bait, as well as three special fish. Two green and one blue. This isn't always the case but typically it is.
Each country has 4 water types. Let's take river fish for example. You can catch River Betty and Salmon. You can also catch fish roe, which is specialty bait for foul water. On top of that, there will be 2 green and 1 blue. The green fish have a low drop rate. You can go 1-500 fish to get one of these. They don't take 500 usually, but sometimes can. Anyone who has fished for the dab in stormhaven can agree with this.
Blue fish had an even lower drop rate. You can go 1000+ casts and STILL not get your fish. It's less than 1% of a chance, surely. Blue fish drop rate are worse than crown crates, take forever to get and are a true reward for those with patience to get them.
Before housing you had a possibility of pulling out any 6 of these items (2 fish, special bait, 2 greens and one 1 blue)
To simplify, catching 12 rare fish in 18 countries (and 1 in 3 islands) takes forever as all know. It's a total of 219 fish to catch (I may be off by a few)
Now with housing, let's cut those numbers down to 33% of what I mentioned above. You now have a chance at any of the 6 fish types before, and throw in an additional 15+ housing items possible to pull on any cast.
This makes the blue fish nearly impossible to catch. Before you had less than 1% to pull it out. And now it's a 1-21 chance, plus the diminished odds of a blue fish.
To simplify again, if it was 1/6 chance (it was worse) for a blue, it's now a 1/21 chance.
So before your good rng pull would reward you a blue fish. Now, it may reward you with a blue housing item, purple housing item, or even a gold housing item. If its 1-100 casts for these items, it now takes 10x(?) longer to pull the blue fish.
I probably am not saying this correctly as far as the numbers go. I'm not a numbers guy. But I do have the fishing experience to tell you it's turned excruciating to grind for a blue fish. I can pull 2-3 purple fish (god i despise this) which comes every 300-400 casts, and before that would be the blue fish needed for the achievement.
Tl;dr - the addition of housing items to fishing has diminished the odds of catching the blue fish tremendously.
As an experienced fisherman, I can tell you the grind has now tripled, quadrupled, if not worse. I have never in my experience went so long between blue fish. It's due to the addition of 15+ possible fishing/housing items added to the loot tables.
Hopefully others can add to this with any other data or experiences. It really ruins a great part of the game. People with the titles better cherish them. It just got brutal.
Please let the fishing items be purchased and removed from fishing itself. The grind was bad enough before!