That type of defenseman can still work in the NHL. I think John Carlson is a better example of what the Oilers were hoping Bouchard can become.
The problem is, even if Carlson's only "meh" defensively, that's still a couple of tiers above what Bouchard seems to be in his own zone.
Bouchard's seemingly low give-a-shit meter on defense is what would irk me most if I was an Oilers fan, his indifference to playing defense is just a terrible optic and just exacerbates his defensive shortcomings. While I agree Carlson was the best case scenario, I've always used Shattenkirk 2.0 as his comparable. Bouchard is essentially the same exact player he was in the OHL and has had very little progression in his game overall, he is a defensive liability and it limits his potential role as a PP specialist and at best as a 2nd pair RD at ES requiring insulation of a defensive beast like an Adam Pelech as a partner.
Now the Bouchard vs. Dobson debate has been going on since pre-draft and Dobson is thriving right now, but I think you really have to factor in the teams and development circumstances between the two players so far in their careers in their current diverging paths.
Dobson had Trotz handling his early development. His regular defense partners were highly regarded mentors in Boychuk, Chara, and now Adam Pelech as a security blanket. Dobson has been allowed to develop while insulated by a strong defense group including Pelech, Pulock (who did a lot of heavy lifting while Dobson developed), and Mayfield. You really couldn't script a better development path and situation for a highly regarded young defenseman. Now Dobson is emerging as the alpha of the Isles defense and doesn't turn 24 until January.
Bouchard's development path and circumstances has been the complete opposite. Edmonton has long had defensive issues and goaltending issues, revolving door of coaches, etc. Bouchard is offensively talented and putting up points as he was always expected to do, but he has had many obstacles in his way.
While I think Dobson has always been the the superior prospect and player, you have to wonder how things would look now between the 2 players if Edmonton had taken Dobson and the Isles got Bouchard.