I'll be honest. If this game is going to survive it will be absolutely mandatory for it to:
1-Massively increase the size of the existing maps and add additional locations.
2-Give players the ability to trade with one another. I mean, come on Bungie, surely to goodness you realize that every other RPG on Earth has that option.
3-Give us the option to name our Guardians and customize their height and body build. This is basic stuff here, get with the program.
4-Ability to customize firearms, such as barrel length, color, magazine size, fire rate, etc. This is a major disappointment for such a well polished game not to have such a basic feature.
5-Make side missions actually worth while by giving each one a story of it's own. I'll be honest here, the side missions of Destiny are the lamest of almost any RPG I've ever played and I've been playing them since Wasteland and the original Final Fantasy on up to Diablo 3.
6-Offer reward options at the end of each quest. For instance, give the player the option of choosing between a rare Encrypted Engram or Strange Coins for completing a mission.
7-Make every planet the freaking solar system available for play. It absolutely sucks that I'm stuck visiting the same locals over and over again. It's boring and greatly detracts from the fun of the game.
8-Give us Class Specific Weapons. For instance, the Titan could carry spiked gauntlets, the Hunter could obtain a short sword, and the Warlock could get Energy Gauntlets.
9-Vehicular weapons and combat on Sparrow and our Ships.
10-Raise level Cap to at least 50. No one likes to see there character level maxed after only 3 days of playing a game. It's boring, and makes the game seem generic.
If Bungie were to do all of these things the game would thrive and stomp it's competition, but as it currently stands, it's just too dang short and repetitive in comparison every other RPG on the market.
Honestly I feel like Bungie didn't really research the Genre enough while developing the game. Either that or they were just lazy, and I would hope that laziness is not the case.