I am not sure why people are so worried about Destiny lacking content.
I put 25+ hours into the beta alone, and it didn't even have all of old Russia unlocked! Not to mention the level 8 cap....
I know people are worried about how the level cap in Destiny will be locked to level 20, but you have to remember that there are multiple paths, or concentrations that you can level up for each character which will give you different abilities and supers to use. Also, a big part of the game will be the hunt for better weapons.
There are 5 different classes of weapons -- Common, Uncommon, Rare, Legendary, and Exotic. Getting Legendary weapons will be hard enough, and require some serious time to be spent in the game, but the hunt for Exotic weapons will be even more epic.
A lot of people have been expecting there to be a massive open world in Destiny (including myself), and are now disappointed. I will not pretend that I was a bit let down, but saying that Destiny will be lacking content is an incredibly ignorant statement.
The world of Destiny (from what we have seen in the Beta) is quite dense, filled with enemies, chest, and dead ghost to find. There are also a slew of activities to do such as Strikes, Story Missions, Raids, Bountys, and free roam missions.
Then on top of that you have the whole competitive aspect of Destiny in the Crucible, and they have also built a social zone (The Tower) for you and your buddies, or clan to hang out and talk, plan strategy, or even have a dance party.
I think the big mistake that most people are making here is assuming that Destiny is a MMORPG.
While it does share a lot of similarities to a MMORPG, at it's heart is is still a FPS, with perhaps the biggest differentiation being that it is still just a $60, and will have no subscription fee like ESO or WoW, and from what we know at least, will not be heavily undermined by a FTP micro transaction system.
Compared to a lot of $60 games out there, especially some of these multiplayer only games such as Titanfall or Evolve, Destiny stands out as having more than enough content to satisfy, and will almost certainly be heavily supported with expansions for those who just can't get enough!