Yes, the number of accounts you create using the WHS Console is limited to 10. It's not possible to change that; it's built into the product.
As for why, well, I would have to speculate that it's a combination of things. Windows Home Server is a home product, and it's rare for a single home to have more than 10 users who will need to access the server. (If you want to give everyone in your extended family an account, how about a generic "family" account that they use for access to pictures and video instead?) Also, a higher limit could lead some small businesses to use Windows Home Server because it's less expensive, where Small Business Server would really be more appropriate. I'm not on the WHS team, I just post a lot. :)
Yes, the number of accounts you create using the WHS Console is limited to 10. It's not possible to change that; it's built into the product.
As for why, well, I would have to speculate that it's a combination of things. Windows Home Server is a home product, and it's rare for a single home to have more than 10 users who will need to access the server. (If you want to give everyone in your extended family an account, how about a generic "family" account that they use for access to pictures and video instead?) Also, a higher limit could lead some small businesses to use Windows Home Server because it's less expensive, where Small Business Server would really be more appropriate. I'm not on the WHS team, I just post a lot. :)