There are only a limited number of bonus action spells, and a large swathe of them are spells designed to be coupled with the player taking the attack action - they're ranger and paladin spells. For the rest, there aren't any breaks or abuses that show up, even if you scan the entire list of BA spells in the current game.
Healing Word into a full spell is extremely potent in terms of action economy and Healing Word into Cure Wounds significantly increases the pace of healing at lower levels. I wouldn't argue that it's broken but being able to do so is a substantial buff. The other standout is Misty Step into Thunderwave letting a player gain high ground, displace multiple enemies from the high ground, deal damage and bonus fall damage.
I've never seen a fair defence of this rule existing put forward that is not better answered by fixing the edge-case situation, rather than punishing all spellcasters everywhere, and why this rule should exist, in defiance of the actual listed part of your turn that it takes up being the only limitation (like literally everything else in 5e).
Bonus action spells for caster classes are generally balanced around the idea that they don't have a zero time cost. If you do set them to have a zero time cost then you need to nerf pretty much all of them because that's a fairly major buff. Any that you don't have to nerf are either edge cases where it doesn't really matter that you can't cast a spell that turn or spells that probably need a buff.
In terms of the specifics you've stated I think there is definitely a case to be made that both reactions in your own turn shouldn't be prevented nor should action surges. But I don't think it makes sense to open the floodgates to high level clerics having a constant stream of additional healing nor Wizards constantly teleporting for little to no cost once they reach a sufficiently high level. To the best of my knowledge those characters are strong enough already and don't need buffs.
