Been playing since.. week 1 or 2 I think? But.. I always saw meteorite pre-EoW since the gold pickaxe (and now platinum and tungsten) state they can mine meteorite (at least prior to 1.4, haven't checked again). I think Bone Pickaxe can mine meteorite as well, which is a much later addition. Meteorite is decent, but doesn't seem a sequence break to obtain it before EoW since the shadow orbs themselves drop items that absolutely shred EoW.. like the ball o' hurt (even moreso now after flail buff) and vile thorn. I'd definitely count these two weapons more powerful against EoW than having meteor armor or space gun.. though I think this is also a combined issue with the EoW being the easiest boss in the game. I think I went in armorless and dropped my flail down, and the boss destroyed itself, while healing me more than it hurt me (hits for 10 or less, getting constantly healed by 20). I didn't have to do anything, no armor, no effort, just a dropped flail and it was dead. Fighting it normally does even LESS damage to you.
I think limiting meteorite after EoW just takes some freedom away from the game- I mean, meteors aren't a guaranteed chance to fall at midnight anyway, and the average new player will probably break 3 orbs first anyway. Having them locked at just one orb gives more knowledgeable players another choice, something I often did. Hit one orb, wait for midnight to see if that dropped a meteor, if not, smash another orb and see.
As for bombing meteorite.. what if there could be sort of a compromise with some form of explosion resistance? Rather than a tile being completely explosion immune or not, perhaps the further out the explosion, the less explosive damage it does to tiles. I try not to make this comparison too often, but.. like in Minecraft. TNT will basically blow up all dirt in its radius, but will destroy less stone within that same radius. Using that concept, I think it could be fair for bombs and dynamite to destroy just a few tiles of meteorite. This could be combined with, or rather instead just, have bombs and dynamite weaken these tiles, setting them in a state as if they'd been hit once or twice with a pickaxe, so that mining them will be quicker.
In short.. I'd like the old requirement of one orb to possibly unlocking meteorites, but also give EoW a much needed buff. BoC seems fine, and meteorite before it should be OK, but meteorite is also sort of OK before EoW, but Ball o' Hurt and Vilethorn are definitely not before EoW. So, EoW needs some extra power. Less chance to drop hearts, higher damage, more defense, more HP.. kind of more everything (but the hearts!). One issue I have with Hardmode is everything is very.. gated. You have to do a lot of things in order. There's still a lot of choice in pre-hardmode, but I just don't like setting these limitations if there are existing bigger sequence breaks- like the very items the orbs themselves drop.
Also a wooden bow with jester or unholy arrows is even MORE effective than using the space gun, which only hits two.. or three segments per shot. EoW is basically a free hand out of shadow stuff.