"Reach maximum level in multiplayer." This phrase is horrid, and yet so many games support it. Halo 2 was probably the first game that really started the shooter leveling fad, but Call of Duty: Modern Warfare refined and polished it into the ripped off experience system it is today. Transformers: War for Cybertron has it. BioShock 2 has it. Halo: Reach has it. Bulletstorm has it. Tron: Evolution has it. All of these games are trying to incorporate RPG elements but they are forgetting a key ingredient.
In an RPG your character progresses as well as the content. But in a multiplayer scenario that is competitive, you can't have the content evolve as you level up, as the game must remain fair and balanced for all other players. This is why games like World of Warcraft work really well, because it focuses on bringing groups of similar experience levels together to accomplish a single goal. While progression systems inspired by Call of Duty try to keep people of similar level in the same matches, the content still doesn't change.
In an MMO setting, a level 18 dungeon is a challenge for characters around that level, but is something that can be absolutely obliterated by a max level character. In a multiplayer setting like BioShock 2? At maximum level you are still playing the same maps you were playing at minimum level. Using the exact same weapons and plasmids you used at minimum level. "But they are a different color! And I have a better scope to improve my aim!" But a sniper crouching in the same camping corner is still a threat to you, even though you are at maximum level and the sniper is at minimum level.
The glory about level progression in an RPG, be it MMO or Single Player, is that the experience evolves and levels up with you. This gives you goals to work towards instead of just increasing the number by your name. And the game also increases in difficulty as you level up too! You are in constant combat with people that have ever evolving skills, be it new spells, better weapons, better armor, or the ability to summon creatures. Where as in something like Halo... a DMR is a DMR no matter what Rank you carry.
The amount of time required to obtain these Ranks is also a ridiculous time sink, especially given the amount of free time that is slowly dwindling and increased outside responsibility that most players have to deal with, be it family, school work, or a job. The part that sucks the most is the lack of rewards for chasing that time sink. In an MMO you have minor stepping stones to maximum level. Mounts, new abilities, unique armor. These short term goals make the long term goals, such as reaching maximum level, way less daunting because you have these minor stepping stones along the way.
Progression modes are a fantastic idea, they just need a bit more refinement to actually include progression, not just a number that increases once you hit a certain amount of points or experience. They also need to strike a balance that keeps players wanting to play and wanting to progress other than 'that sweet new helmet' that is just aesthetic, or that 'ammo capacity upgrade' that gives you four more bullets for a single weapon. Developers need to not only push themselves further, but bring the players along for the ride.