Everything Apple does is to gain more money.
Here's why I personally like MobileMe.
1. If I add something to my Windows calendar or address book at work, that change is pushed to both my iPhone and my Mac at home (and vice-versa). As a result, I actually use my calendar and address book a lot more because no matter where I add a new entry (or edit an existing entry), the info is synched to all of the computers I use.
2. iPhoto and iMovie directly integrate with the MobileMe web gallery, and I like how the web gallery looks. I can control the quality of the pictures, pick the resolution of my movies, give people the ability to download pictures in the same resolution I shot them in, give people the ability to upload shots that I may have missed to my gallery, and I can hide certain galleries from the page so people have to have a direct link to see them.
3. I can access my iDisk from any computer with a web browser. This makes it super easy for me to copy files to and from work. For example, I took home a company-made DVD tonight and used VisualHub to rip it to a WMV format so we can distribute it all of the PCs at work. I put the result on my iDisk, so tomorrow when I get back to work, it'll take like 30 seconds to download. Or if I'm at work and download some MP3s from Amazon.com, I can pop them up on my iDisk and pull them down at home.
Pretty much all of those features can be found for free on various websites across the Internet, but I don't have to hassle with a different sign-on for each website, and I like how each of these features integrates directly with my Mac.
There's a lot to MobileMe. If you're only going to use one feature, then it's probably not a service you'll feel you'll get any value out of.