I totally agree with you, the points you made were exactly my points.
*I NEVER shipped Brandon/Kelly for the sake of wanting Kelly with anyone but Dylan because of the Dylan/Brenda romance. I shipped Brandon & Kelly since the first season, like you. There was major flirtation going on and it was obvious where the writers would eventually go with their relationship. Darren Star says on the dvd commentary that they'd planned BK since the beginning, but they wanted to wait until Kelly had changed asa person. I was shocked they waited so long, to be honest. But I was thrilled when it finally happened. The chemistry was spot-on. They were hot together at the Spring Dance & I was shocked they had Brandon kiss her like that, then have him reject her the way he did. Even though I sort of understood his reasoning behind it.
*Seasons 4 & 5 & the last part of 7 are my favorites. TOTAL B/K sweetness, and the writers clearly respected their relationship at these points. I also noticed the best writing staff wrote the BK & DB romances, as in many of the original writers, which I think speaks volumes of how highly they thought of these relationships. I was kind of upset at some points though - when they have Kelly constantly conflicted over her feelings for Brandon & Dylan; & when they have her miscarry & being told she might not be able to conceive again. I thought that was unnecessary - Brandon & Kelly would've made great parents. Great married parents.
*Which brings me to the disaster that was Season 8. The only explanation I can give is that clearly Jason Priestley expressed his wishes to leave the show at this point, & the producers had already planned to go on with the show another two years, & wanted Jennie Garth to stay, & so they thought of the harshest, most contrived ways to split Brandon & Kelly up, which would allow for the Dylan/Kelly end union. It's painful beyond words, & I never watch beyond where Kelly's amnesia after being shot goes away & she remembers Brandon, because it all goes downhill from that point. It's just terrible that the writers not only have Brandon cheat on Kelly with some stranger because life was too "perfect" for them, but also have him tell Kelly he doesn't want to marry her on their wedding day. This goes down as the most awful 90210 episode for me personally, I can just never ever bring myself to watch it, knowing what is coming.
90210 for me more or less ends at Season 7. They bring Kelly & Brandon back together with that beautiful story about the ring, then they tear them apart. It's terrible. In the perfect version of 90210, Kelly & Brandon would've got married, had the baby, & had a double wedding with Dylan & Brenda.