A spore druid multiclass for constitution saving throw proficiency is ridiculous - you might as well use the feat you would have lost from the multiclass on Resilient: CON.
I like it on mine (though she's Land, not Spore). She gets heavy armor as well, boosting her armor class, no need for dex, so I can use some of those stat points elsewhere, and, being a halfling, getting to a +9 on con saves means most concentration saves now essentially have advantage. So, feat-wise, I basically have War Caster with the reaction swapped out for heavy armor, a higher con save, and the ability to use all martial weapons. And I got to use Resilient for Wisdom, giving me +1 there and better saves against various control spells. And that martial weapons bit does open up some stat stick options, particularly for the ranged weapon slot. And what does it cost me? Well, level 12 doesn't get me any more spells per day. I do lose out on another prepared spell slot, but I already have 8 extra of those due to my subclass. If I felt the need for more, every other druid subclass would be absolutely boned. As far as that goes, it costs me nothing of value there. But there is another cost, and that cost is probably the reason why your PnP players regret the MC choice.
And that is that my druid stuff is delayed by one level, once I hit level 6 and added fighter to the mix. One could say I've also delayed the feat by a level, but that depends on if I'd feel the need to take War Caster at 8 if I hadn't taken that level of Fighter. Still, that delay can feel painful, though, honestly, I'm perfectly content with my Spike Growth and Call Lightnings so far, so whatever. This, though, I think is a lot more impactful in pen and paper, where more real life time passes to get a level, plus the cap isn't there and yattainable, unlike in BG3. The level cap is quite likely something most PnP players will ever reach. Added to that, there's enough xp in this game that you can outlevel the enemy level curve, which is something that wouldn't happen with a live DM at the helm. So I do wind up having the spells appropriate for the encounters in game. If I was playing pen and paper, I wouldn't multi-class.
And that said, there is the question of whether or not I want a second level of fighter. A lot of people would, because Action Surge. That would, however, cost me the 6th level spell access. So I'm not sure which route I'll go there. Thinking I'll probably go 1/11 fighter/druid, though.
As far as flavor goes, I'd say dual wielding melees do want to the MC. Problem with DW is that the off-hand attack uses a minor action. You only get one of those, so you only get to swing 1x per turn with that off-hand, which doesn't exactly feel very dual wieldy. However, the Thief subclass of the rogue gets an extra minor action at level 3, meaning it can use that off-hand twice... except it only gets one attack, so that means nothing. So to get your Drizzt on, you want to combine a class with the bonus attack with 3-4 levels of Thief for the extra minor action. And, yes, this will cost you an extra main hand attack, so the number of total attacks essentially stays the same. But at least you are using both weapons more now. And if you go 8/4, then you don't lose out on a feat either. Of course, there are other trade-offs. You don't get the stronger maneuvers a fighter would get at 10, for example, but on the plus side, you do get some sneak attack damage and the other early rogue benefits. It is still kind of unsatisfying in some way, though, because you're looking at level 8 before your character finally has 2 off-hand attacks to go with 2 main hand attacks.
Also, one other factor to consider: your players most likely can't respec for the low cost of 100g.
