Why must it be this way? At higher levels the monsters strike first. At low levels new players can't handle getting attacked without warning. When your character starts off they are too weak to handle aggressive monsters. These and many more lame excuses give us the tedious grind of MMO levelling. While I can understand that you don't want to give players too many powers to start off I don't understand why murder safaris are necessary.
Remember Megaman 2 (Rock Man 2 for our Japanese and Dark Otaku* readers)? In it you have to defeat several bosses. You can choose to tackle their stages in any order. Each of them gave you a weapon that was super-effective against another boss. This formula could make for an excellent MMO experience. Instead of needing to level by killing zillions of monsters I would set up a loop of interesting challenges for the player. At the end of each challenge the player would earn a new ability. The order you tackle the challenges could be up to you, to a degree. Now I know that you're thinking it's easier to throw in monsters than create challenges, but what if you made simple challenges that put the monsters in a different perspective?
Here's one idea: the stealth challenge. The goal is only to get through the field of monsters to the other side. The monsters will attack if they detect you (MMOs can have various kinds of detection and methods of avoiding or suppressing it). If the gains from defeating the monsters are not worth the time it takes to do it, players will learn to avoid the fights and sneak past everything. Then all you need to do is put a stealthiness ability as the reward for a different challenge and you've created the first link in your loop of abilities and challenges.
Note: it is not cute to reward the players who successfully stealthed with a stealth ability - they don't need it if they are already good at it. Put that ability somewhere else so that players who are bad at stealth can get it before they tackle this challenge and those who are good at stealth can start with this challenge and use the reward ability to help them with a different kind of challenge they are less adept at.
Some other MMO challenge ideas that involve monsters but not just senseless murder safari**
- Wolf in Sheep's clothing: in a field of sheepy monsters, find and kill the one that's not quite right.
- Timed escape: similar to stealth, but detection doesn't mean failure, it just means wasting time fighting. Perhaps there is one fight you can't avoid near the exit and finishing it as fast as you can is key.
- Get chased: get a particular monster to chase you, then lead it to a certain area. Run too far ahead and it will lose interest, too slow and it'll kill you (unless you heal a lot). Variations include a 2-player version in which you must get two monsters to cross paths so they can fall in love.
- Multi-switch puzzles: Throwing levers and standing on switches to open the way forward. These are especially fun when designed for groups of players. (Monsters are incidental here, fastest to avoid them but clearing them out is allowed.)
- Tag: You must touch each monster once, but not twice. Good luck keeping track of them as they move around. Can be brute-forced by having enough friends helping by each following a monster so you don't lose track.
A game's design doesn't even need to go this far to avoid grinding. Remember that the players will find the most efficient way to level up. Simple make killing monsters inefficient compared to quests or crafting or whatever you want your game to be about and players will soon realize which is the optimal path.
Look, it's not that I don't love a good battle against a monster. A good battle. I love the boss fights in which you have to team up and figure out the best way to defeat a challenging enemy. Better to spend your design time on 20 interesting boss fights than 100 dull monsters for players to grind on. I could imagine a game with only boss battles. The first few fights that can be tackled at low levels; they could reward enough exp for players to gain entire levels; they could be fun to repeat a couple of times, especially with different player (and class) combinations.
*Dark Otaku - fans of anime and Japanese culture who have an elitist attitude toward fandom. They have low tolerance for new fans and non-fans, and love to emphasize the Japanese versions of things over their American counterparts. Contrast with Light Otaku who, while having equally deep knowledge of anime and Japanese culture, love all fans and have a more positive outlook on fandom.
**Yeah, I just love writing it. MURDER SAFARI!