No, it's not. But that's not what you said. You said, "First level PCs should really not go anywhere near a blue dragon or a town filled with bad guys." That's metagaming.
Are you seriously telling me that you did not understand what I meant?
Inexperienced adventurers not engaging in a straight-up fight with a dragon is not the problem. Inexperienced adventurers totally throwing in the towel and not doing anything because there's a dragon overhead and first level characters don't have the hitpoints to withstand its breath weapon, yeah, that strikes me as metagaming.
Again, semantics. The game is played with a set of number which indicate how strong a game element is. PCs would know that the breath weapon of dragons can burn down an entire village, hence, they know that it would burn them to a crisp as well. The players do not need to know if this is 12D6 or 16D6 or 20D6 of damage, they just know that it's probably a large number of dice.
As I've said repeatedly, PCs are not expected to want to fight a dragon head on, but neither are they expected to completely avoid danger. Nor are they expected to think "dragon = impossible to defeat".
"Nor are they expected to think"... You hit the nail on the head. The game designers (and hence people like yourself) expect the PCs to think in a given way. But guess what? Not everyone thinks in the expected ways, some people think in a more rational "dragon = impossible to defeat" way.
And the expected "dragon is not equal to impossible to defeat" is the metagaming aspect of this. Because it is a module, players are expected to metagame that their PCs will survive an encounter with a dragon.
That's backwards thinking.
Does it really make sense for PCs to approach the dragon so that they get hit full on with a breath weapon right off the bat? I mean, it's not exactly like they stumble across it without meaning to. Reidoth tells them about it and the Folk Hero knows where it is.
I can say the same thing for the other module:
Does it really make sense for PCs to approach the town (or the parapets) so that they get hit full on with a breath weapon right off the bat? I mean, it's not exactly like they stumble across it without meaning to.
The contradiction from one module to the next is there, even if you refuse to admit it.
With regard to LMoP, the folk hero only knows that it is in the town (IIRC, I do not have the sheet in front of me). What if the PCs do not go to "building 4" and talk to Reidoth first?
What if, even if they know that it is in the tower, it attacks them with breath weapon when they get close anyway? Why do DMs insist on playing Dragons with Int 16 (smarter than most of the PCs) stupid? Why does this dragon with a good +7 Perception not hear the PCs coming or fighting in the next building over? Why is he not truly prepared (i.e. ready with breath weapon)?
The dragon isn't attacking PCs or NPCs. It's the Dante Hicks of dragons. It's simply strafing the tower with lightning. It doesn't know PCs from NPCs. Why would it suddenly pick out the specific characters from the dozens of men firing arrows at it? The encounter is set up like a skill challenge (prevent 10 soldiers from dying), but that doesn't mean the characters or the DM can't change the stakes.
Except if the PCs head out onto the parapets and damage him, shouldn't he breath weapon them as well?
Oh right, it's a module written that the dragon won't do that (either that, or PC death).
Some people do not like encounters with Dragons fighting with kid gloves on (pulling their punches is how someone else described it).
If you like playing that way, great. It's implausible to me and kicks me out of my in game verisimilitude.