Okay, it's time for me to make a giant big wall of text.
The reason why people like mods from different people is they will all have different ideas. One person thinking of ideas like Marble Blast Red, Green, and Blue (generic, but examples) are going to run out of ideas (a mod usually has new powerups (and even if they don't, they use things that are new. For example, teleporters in Marble Blast Platinum.) and features. Marble Blast Platinum has teleporters, more in the GUI, Leaderboards, achievements, etc.). Marble Blast Advanced had a speedometer. Usually, if one person makes three mods, they are going to reuse ideas, making only one mod spectacular for unique ability. For example, if they did Red first, unless this is their first mod, it will be only good because it then is released first (usually) and praised, until Green and Blue come out and, what do you know! A bunch of reused levels. Chances are nothing else is going to be shown. Unless you have something that everyone will then praise the mod only for bringing it in (Marble Blast Blue, say, getting water, Green getting acid).
My current, well, technically completed and lost, mod that is now in development, is really more of a bunch of my custom levels in a 100-set. The community would rather prefer custom levels over mods right now, because now we can care about misalignments and professional working more. Now I'm building a bunch of 2007 like levels, because I want to bring my past back. It's fine to me, and making that horrible 100-set that should really be forgotten (not this one, the MBG interior-taking level-editing) was made in a huge rush, trying to remember things. Honestly, if anyone is JUST like me trying to remember things, go and try to play other people's levels. I found Ralph's 22-set of levels and remembered 2 levels perfectly after that. Now let's not get into detail about which two, but it works for me.
Ever wonder why so many mods wind up in the trash? Many people lose interest in making them. They also require coders, which I had to do myself. I don't know a lot of code, but I can easily navigate and, heck, still remember what's going on. Honestly, if one even bothered to look at the .cs files, the comments (//) are quite user-friendly, intentional or not. I changed the 7-second PowerUp time to a 5-second one. I made six types of times in different colors, which seems to be a problem. I explored MBP's way of doing it and figured how to do six different ones, which are not too much of a problem.
Joining other people's mods are a great way of having different and unique levels in a mod. After all, 100 is a big bundle to shoot at for one person. This particular mod took around a year, maybe more. It had different graphics and a style based off of fun. I don't know what Marble Blast Platinum's style is, as MBG seems to shoot for cartoony while MBP seems to hit realistic. MBA hits...sorry, but I can't think of a name for it. technical? MBF hits even more realistic. Some mods don't get a style before they're thrown in the trash. Making a mod that takes interiors from other mods just seems more like copying, and why even my failure of making one, Gauntlet gives you a lot to work with. Gravity changing is not even needed, just a bunch of SUPER GYROCOPTERS! Meanwhile, Learning to Roll only gives you a gravity modifier and maybe rolling on the edge to turn it into a tightrope level.
It's been two years since I've changed my name, changed how I feel, (didn't change my writing style), upgraded my Intelligence, age (um... yeah), attitude, (didn't change how I made levels), changed my password (Yeah. I don't actually remember my old one.), likings (not this), and a lot of things. Many people know me before and after, and I certainly still know a lot of people.
Here are my level ... types:
Thoughtful - Usually these are fun, as they rely on PowerUps. Some levels require not much, for example, obviously a Gyro and a super jump will lead to a big jump. However, the smarter levels will do other things: Take the gyro, use it, take the super jump but don't. After that you need the super jump for some reason. An example is Combo Course.
Puzzle - Use the environment to your advantage. PowerUps here usually come one by one, instead of all at once. This can overlap with Thoughtful. My most recent level, which is not really recent anymore. If a PowerUp is singular, and you can't do much to get another PowerUp, you probably need to wait for it to respawn and use it twice. An example is Slope Madness.
Speed - Usually uses a lot of insta-boost PowerUps like Super Jumps, Super Speeds and Gyrocopters. You are not likely to see the more passive PowerUps (well the Gyro is passive, but has more use). For example, Speed Attack in MBP is a Speed level. However, this can also apply to levels with a low par time, including Battlefield Finale.
Training - That's about it, really. It just teaches you. For example, 3/4ths of the Beginner section, and Tutorial section in the case of MBF.
Maneuvering - Usually without any PowerUps, and if they do have them, they are singular and not needed for puzzle-based things. PowerUps do not lead to the next one in a tricky way, and usually have gems, but also have a bunch of wall and edge hits. For example, Crash Course or Strategy Climb would do it. Crash Course is a pure Maneuvering level; Strategy Climb uses PowerUps and, notably a bumper shortcut.