Cool, play as you like.
It was overwhelming the most highly regarded, most completed, and most appreciated campaign 5e have released. Hard to find it as bleak as you suggest. Maybe everyone is wrong though and it really is dull.
I think Lost Mines of Phandelvar is mostly looked at with rose colored glasses, because it was the first 5e adventure most people came in contact with. It was also my first D&D adventure ever. And that of my DM and actually 4 out of 6 players.
But even while running it, we beginners could see the many problems LmoP has.
First of all: it is not beginners friendly at all. Inexperienced DMs and Players will probably get killed very quickly in the beginning.
The Goblin Ambush or the going trough the first goblin dungeon has probably killed more adventurers 5e adventuring groups than any other published or homebrewed adventure.
The motivations to stick to the adventure are also non-existent and we had some players who's characters (everybody made their own) really struggled to find reasons to stay on course and not just leave to go somewhere else. As far as I remember their is literally no good reason to stay in phandalin after you rescued the NPC from the first Goblin dungeon. Non of the NPCs are memorable (like I literally don't remember anyone right now) except for the Nothic (who my character wanted to save, but had to kill in the end because he would continue to pose a threat to the village and there was nothing in the adventure to give him a backstory that we could use to transform him back).
And the story beats are disjointed. The Green Dragon has nothing to do with anything.
The lost mines by itself are a mess to navigate, describe and run, especially for newbie dms and players ...
I mean, I could go on.
But I think the only saving graces of LmoP are that it was the first 5e adventure (so people didn't know better) and that it was short.
I'm sure experienced DMs (which are the target group of early 5e, to be fair) can run it just fine, but if you give it to a Newbie to run you are lucky if he doesn’t quit D&D.
Stormwreck Isle, even with all its Flaws is a way better Beginners Adventure.