I would think more bowlers are going to the protective tape on the backs of their thumbs than anything and most of the texture is 'grippy' similar to white tape

Would you agree or think it's as much protection as grip support?

I need to buy stock in Vise, I sell out of the hada patches SO fast. 

I personally can't stand the stuff, and it's not because it isn't good and it's not because it doesn't work, it's because for 90% of the people that use it, it's a crutch so they can grip the hell out of the ball without ripping their thumb open.  If you have a good fit and don't grip the ball through the release, you should be able to bowl SEVERAL games a day without any issues.  The vast majority of the people that use it are in the shop quite frequently needing the thumbhole buzzed out.  They aren't getting blisters, their thumb is just ballooning out. 

I use the smooth Hada tape so I can have the hole a little tighter and get a quicker release. IT thumb slug so I rarely need black or white tape. Definitely a lot of people using it as a crutch,along with cork, tape and whatever else they can jam into a poorly fillting thumb hole.

Without using cork, tape and whatever else...What is a good fitting thumb hole?
At what point is it a good fit if the thumb swells and shrinks periodically?

Earl Anthony ovaled his thumb holes simarily...used white first aid tape and placed around the hole to fit the desired release.

My thumb is oval. I do not drill it oval. I drill a 15/16" hole which is a bit large and add two pieces of white tape in the front at 2-3 o'clock and then three to four pieces in the back at 7 o'clock. It puts the tape perfect on the front and back sides of my thumb to make the hole fit perfect. I can relax my hand in the ball and feel nothing with the tape. The back side does ware down and isn't really an issue for irritation on the skin.

Now as the weather changes I can add or remove tape as needed and always have a very consistent fit in every ball because they are all the same. For me it is a very simple and relaxing fit.

I use the same basic technique and philosophy for taping. But I've never been able to have a final exposed piece of white on the back. For my skin, it's too abrasive. As a solution, I put a piece of Master Quik-Release tape on the final piece of white so I can get out clean. The Quik-Release tape is very thin, and doesn't noticeably change the size of the hole.
 
Before anyone suggests it, I don't knuckle the ball. I have a tight hole with 1/8" forward in the thumb.   

Did you guys try the TIERED TAPE technique?  Check out Coach Joe Slowinskis' site and on YouTube on how to do this.  I had a problem with knuckling my thumb and there was a callous on the back from doing this, and this is with using Vise tape on the back of my thumb.  I actually started getting it when I tried the Magic Carpet, and it's been with me ever since.  With the TIERED TAPE, I no longer knuckle the thumbhole, and the fit feels really good. I can really relax my hand and get a nice smooth release. 

I think if you can feel the ridges then it's not fitted  right. Yes, it is pain staking and does take time and experimentation.  It took me several tries to get it pretty much where I want it to be. I don't feel any ridges. I'm glad that you tried it and I agree, it's  not for everyone.