[CTcard]

8 out of 16 regionals at SEC schools. Fair?

ACC gets 4, then P12 and B12 with 1.

Sun Belt and Missouri Valley also get 1 each.

Bias? What bias?

The SEC really has the RPI formula down. Rack up tons of wins versus the myriad of very weak teams across the south, then through league play your opponents' records (half of RPI) is always really strong. So, the SEC has 6 of the top 8 in RPI and 7 of 11. 

The RPI is terrible for what the NCAA uses it for, but since they obviously use it heavily one has to discuss it in considering tournament seeds. The power ranking I prefer is the Iterative Strength Ranking (ISR) by Boyd Nation who runs Boyds World web site. 
NCAA Division I Baseball -- Iterative Strength Ratings (boydsworld.com)

Auburn seems the most ridiculous choice of host. I guess their 17-13 SEC record is just too good to pass on, despite an overall record of only 34-21-1, 1-2 at the SEC tournament, and an RPI of 19. Poor Tennessee, the only team above 0.500 in the SEC (16-14 then 0-1 in SEC tournament) that didn't get to host. 

Coastal Carolina seemed to get a host spot based on fond memories of their 2016 title. Always hard to compare major conference teams to mid-majors, but consider Sun Belt champ Coastal versus Big South champ Campbell.
Coastal: reg. season champ by 1 game; lost in semifinals of SunBelt tournament, 39-19 overall, RPI #14, ISR #27
Campbell: reg season champ by 1 game, won Big Sourth tournament, 44-13 overall, RPI #13, ISR#19 

A team I don't resent winning a host position but I wonder about is this year's mid-major darling Indiana State of the Missouri Valley Conference. They ran away with the conference regular season title (24-3, won conference by 6 games), won the conference tournament, #9 RPI, #17 ISR. 
However, in their out of conference weekend series they went: 0-3 vs Northeastern, 0-3 vs Kentucky, 3-0 vs Memphis, 0-3 vs Michigan State. Not impressive. They did pick up a couple of midweek wins against Big Ten teams and one vs Vandy, but midweek games are often experimental for major conference teams. 
I suspect they'll have a brobdingnagian fan turnout for their first ever time hosting a regional, but might be a good place to be a #2 seed. 

As for the Pac 12, Oregon State blew their chance at hosting by going 0-2 in the Pac 12 tournament - you have to be in the SEC to do that and still host. 

For Stanford, the best part of their resume is winning the Pac 12 by 5 games. That ought to be enough for a top 8 seed by itself. The downside is mostly an RPI of #15, but that's the way the RPI goes. An hour plus away from the announcement, I will stick with believing they'll get a top 8 seed, but not higher than 7.

[CTcard]

8 out of 16 regionals at SEC schools. Fair?

ACC gets 4, then P12 and B12 with 1.

Sun Belt and Missouri Valley also get 1 each.

Bias? What bias?

The SEC really has the RPI formula down. Rack up tons of wins versus the myriad of very weak teams across the south, then through league play your opponents' records (half of RPI) is always really strong. So, the SEC has 6 of the top 8 in RPI and 7 of 11. 

The RPI is terrible for what the NCAA uses it for, but since they obviously use it heavily one has to discuss it in considering tournament seeds. The power ranking I prefer is the Iterative Strength Ranking (ISR) by Boyd Nation who runs Boyds World web site. 
NCAA Division I Baseball -- Iterative Strength Ratings (boydsworld.com)

Auburn seems the most ridiculous choice of host. I guess their 17-13 SEC record is just too good to pass on, despite an overall record of only 34-21-1, 1-2 at the SEC tournament, and an RPI of 19. Poor Tennessee, the only team above 0.500 in the SEC (16-14 then 0-1 in SEC tournament) that didn't get to host. 

Coastal Carolina seemed to get a host spot based on fond memories of their 2016 title. Always hard to compare major conference teams to mid-majors, but consider Sun Belt champ Coastal versus Big South champ Campbell.
Coastal: reg. season champ by 1 game; lost in semifinals of SunBelt tournament, 39-19 overall, RPI #14, ISR #27
Campbell: reg season champ by 1 game, won Big Sourth tournament, 44-13 overall, RPI #13, ISR#19 

A team I don't resent winning a host position but I wonder about is this year's mid-major darling Indiana State of the Missouri Valley Conference. They ran away with the conference regular season title (24-3, won conference by 6 games), won the conference tournament, #9 RPI, #17 ISR. 
However, in their out of conference weekend series they went: 0-3 vs Northeastern, 0-3 vs Kentucky, 3-0 vs Memphis, 0-3 vs Michigan State. Not impressive. They did pick up a couple of midweek wins against Big Ten teams and one vs Vandy, but midweek games are often experimental for major conference teams. 
I suspect they'll have a brobdingnagian fan turnout for their first ever time hosting a regional, but might be a good place to be a #2 seed. 

As for the Pac 12, Oregon State blew their chance at hosting by going 0-2 in the Pac 12 tournament - you have to be in the SEC to do that and still host. 

For Stanford, the best part of their resume is winning the Pac 12 by 5 games. That ought to be enough for a top 8 seed by itself. The downside is mostly an RPI of #15, but that's the way the RPI goes. An hour plus away from the announcement, I will stick with believing they'll get a top 8 seed, but not higher than 7.