For the MP is it going to be like Halo 3 where you're matched up with people who are close to your rank? It's bullshit that a level one person is getting matched up against someone who has hours invested into the game. In CoD it's one thing due to the starting weapons be decent enough for you to defend yourself and you're health is the same as everyone else, but in Destiny you're screwed.
There will never be level based matchmaking.
The current matchmaking algorithms prioritize connection, and second on the list is skill.
Getting level cap in Destiny is not that hard, and if you feel like you're at a disadvantage, you should just finish the campaign. Level based matchmaking would just encourage people to make new characters to wreck the shit out of new players.
Although, the gun you start Destiny 1 with wrecked
during the AR meta in year 1.
It was good enough that they made an exotic version, that with very similar stats holds up in year 3.
Really, Lv 1s are more than capable of killing Lv 40s, and if better, rarer guns didn't give you an advantage, however slight it honestly is, there would be no point to playing the Crucible.