Why should I learn and use struts?

I would look longer term than this project. As you saw, first time you use any technology is largely about making mistakes and learning from them. So this first project won't likely be a shining example of Struts usage once you're done.

Using Struts (and Tiles from what you indicate was a main concern: JSP copy and paste) will however be an excellent delve into "proper" MVC, i.e. it forces you to do things in a particularly structured way, and one which I happened to appreciate a lot, I was a big Struts fan.

That said, there are other options, e.g. Spring contains Spring MVC plus much much more. If you're going to invest in overcoming a learning curve, think about which framework will most benefit you overall in the medium term: which frameworks do employers in your area tend to look for, for example? At this point in time, I would go with Spring where I feel the momentum is but Struts is very good at what it does.