Well, good news, there are some fun spells in D&D5e , even the cantrips. Many of them have interesting secondary effects added that are tactically useful and fun, like the pull effect of the vines, the summoning weapons that attack the enemy every turn, the flaming/waters sphere you can roll over tthe enemies "Raiders of the lost ark" style, the knocking effect of gust of wind and tide, planar shifting, merge into stone if they apply that... I am sure many of the spells would appear in the games.
Bad news, most of them you can only cast once at a time, due to the concentration mechanics of 5e. I´m not talking about the one that allows you to disrupt the caster´s concentration dealing damage to the caster, that makes sense. I am talking about the fact that you can only concentrate on one spell at a time. Many buffs do not reach the entire party of four, most of them are f unless you heighten, are for only them and require concentration, so you lose them if you want to cast offensive spells. Heck, you cannot maintain the paralysis in a creature you have with "hold person/monster", maintaining an animal/creature conjured (besides creating undead and similar, that are not that good in versatility or offensively unless you are a necro or similar) or cast a wall of fire or a storm without losing the previous spells.
I understand the need of those if you want to make a more dynamic tabletop game, with a faster pace and let your players focus on roleplaying and having fun... but I do not know if that simplification of the rules are really necessary for a videogame, where the game engine makes all the rolls for you no matter how complicated they are, takes care of all the calculations for all the spells you have activated and makes the enemies turn faster than what a human DM usually could achieve.
Those mechanics that make a roleplay table session more dynamic and fun make the videogame experience more limited than it could be. And I talk specifically of the concentration mechanics. Plenty of options for your casters, but they are reduced to cast cantrips or make the same tactical combos in every fight because they could only maintain one spell at a time so other combinations are forbidden. Double that because neither Solasta nor Bg3 allows multiclassing right now so you have to deal with one spellbook.
Solasta, even tho it makes the warriors more interesting, still has this limitation when you play casters. It follows very tightly the rules of D&D5e, so almost all the spells of the SRD are in the game, which is good, and they are applied as it is, purely RAW. In my runs I usually find myself repeating the same combos again and again even when trying new characters due to that limitation. They show you all the candy, but they only let you get one. You get the impression of a loss of potential of that formula, so many cool things you could do if you do not have to deal with the limited (for a videogame) concentration mechanics.
Bg3 added some interesting mechanics that allow you to have more options in combat. Since they made some rules changes I am still hoping that the devs or some mods would offer a solution that could make you have more versatility when you want to play pure casters. In D&D5e you can even make parties of casters-only so this addition would be very welcome.
I agree with much of this, and do believe the intent of 5e was to try and achieve a middle path between 2e and 3.5e, both in things like wizards/fighters being too powerful or not powerful enough, and in things like 2e being very simplistic with gameplay mechanics and rules options while 3.5e was criticized for rules "bloat." The open question, though, is whether and the extent to which they were truly successful in achieving this middle path. I personally still find 5e to be unfair in how lame the fighter class is, and also find the overall gameplay mechanics to be on the simplistic side. I especially don't like that in 5e the distinctiveness between classes has been watered down. If you are going to have a class-based system, the classes need to (strongly) mean something.