I don't disagree with any of that, really, but I do think that it's more interesting having the companions fall in love with, say, each other.
Actually, this brings up a point that I haven't talked about much. A lot of people HATED Capaldi's first season. They point to some of the really stupid episode stories (e.g. "That one with the trees" or "The moon is a freaking egg?!") as a reason for why. Personally, I LOVED Capaldi's first season. I thought that was the best iteration of Clara we got. Moreover, I really, really enjoyed how Clara had become torn between having a normal, settled life with Danny Pink, and going on fantastic adventures with the Doctor...and how those adventures ultimately cost her the life of the man she loved (Danny). I watched throughout the season and I enjoyed her internal struggle about normalcy vs. adventure, which I think is a very, very real struggle for a lot of people who are in their mid-to-late 20s or so. Clara wanted it all, and learned that you can't have it all at once. Finally, I thought her finale that season was perfect. Danny was gone, turned into a cyberman (the Brig with him), but he was a good soldier to the end. And Clara was left to pick up the remains of her life. Suddenly, traveling with the Doctor just wasn't a grand adventure anymore. Suddenly, it had a real cost. Clara was a little broken at the end of her journey there, and as she walked off to go find the boy that Danny had mentioned, I thought it was the perfect exit for her character.
That arc was TERRIFIC. I didn't care about the whole "teased at the end with Missy being the Master" thing and it being typically Moffat ass-pulling. Moffat had more than delivered on Clara's character arc. She'd grown and changed, and it all held together. I didn't even really mind when she came back for one last hurrah in the Christmas special. I was looking forward to Faye Marsay taking over as the companion, too.
But then Moffat went and Moffated all over the story and just brought Jenna Coleman back with a waive of his hand and a "But who cares about what happened last season? On with the show!! Yay!" Clara was back, with a new personality ("Adventure junkie and wannabe Doctor herself!") but not a lot of insight into the why or whether that was just a facade for a broken person. It didn't matter! She was back! On adventures! With the Doctor!
Anyway, before I get off on a true Moffat-bashing tangent, I want to point out what I thought Capaldi's first season did so well and why it did it well. It took Clara and it fleshed her out. It gave her a life outside of the Doctor, and showed the pull of that life, and how it conflicted with her life with the Doctor. It also showed the draw of life with the Doctor. And it showed the costs of traveling with the Doctor. Moreover, unlike (for example) Rose, who basically just kicked Mickey to the curb and ran off with the Doctor, Clara really seemed torn about it all. The writing and acting conveyed that internal conflict well, too. What I'm saying here is that I think it's really important that the companion not be JUST in love with the Doctor, and that there is rich material to be mined from a companion having a separate life, and what it means for that companion's "home" life to travel with the Doctor. I would argue that this was one of the great successes of the Rose era, too, and with Donna. However, I found it pretty lacking in the Martha period, and with Amy as well. For that matter, it was also missing from Clara's early season and the final season she was in, which I think weakened those seasons.