For starters, even ignoring the dislike, there is an inherent trouble for me with bichirs and cichlids that deals with a lack of appeal and more trouble than having them is worth.
Bichirs are too drab for my taste, and many, many cichlids are either too drab (eg: wolf, oscar, jaguar, convict, uaru, many pike cichlids) or too much work relative to reasons one would want to keep them (eg: discus, Malawis, Victorians, Tanganyikans) for me. To elaborate on the latter a bit, I'd rather not spend ages and ages with, say, ensuring I don't stunt notoriously sensitive young discus or ensuring my Malawi/Victoria/Tanganyikan tank is properly overcrowded, the mbunas aren't eating too much protein, increasing the pH, the cichlids aren't hybridizing, etc.
Moreover, all species of bichir that I know of as well as many of my least favorite cichlids (here's looking at you, oscars) are just plain unsuitable for my tanks looking at size alone. No matter if it's my favorite or least favorite pet, I hate the thought of having a tank too small long-term for the fish in it and no plans to upgrade.
Add in to that the fact that many bichirs and cichlids are well known for bullying and/or devouring innocent community fish, as well as the fact that there are plenty of accounts on MonsterFishKeepers and elsewhere of bichirs and cichlids actually doing this to said innocent community fish. Worst of all, I have read far too many cases of my absolute favorites, clown loaches and pictus catfish, getting bullied and/or eaten by bichirs and cichlids (especially my absolute least favorite cichlid, the oscar). Additionally, there is (or was, it was either bought or died) a clown loach at my local Big Al's that was put with some mbuna and was on the verge of death (cloudy eyes, scraped up, 'pinched' behind head), that I felt incredibly bad for and would have rescued in a heartbeat had my tank space allowed for it.
And
this is where a simple lack of desire and lack of ability to care for said bichirs and cichlids turns into a full-blown dislike. Truth be told, I was actually quite happy when I read one thread about a red tailed catfish
eating 3 oscars (which, in a way, avenges some of the innocent pictus catfish that were eaten by the nasty, ogreish oscars).
Plus, on top of all that, my stocking plans for all my tanks don't allow for space for any more cichlids.
So to all the bichir and cichlid fans reading this, call me as irrational or as spiteful as you want, but my strong dislike for and vow to never get any of these fish is much better than my innocent loaches, catfish, and community fish being bullied or eaten by nasty bichirs and cichlids that will get too big for my tanks.