i currently have a squier strat. and have been playing for 8 years. why would i ever get a new guitar?
the different wood's give the guitars different sounds... and you might want a different guitar for different types of music. Squier strats are typically beginers guitars. if you are fine with it, i dont see the point in spending money on a new one.
Upgrading to a better model.

Some guitars are better for different genres, e.g. Ibanez's are really good for shred and metal since they have a smooth and light neck which people can wank about on.

While others, like Gibsons are good for Heavy Rock since they are big, chunky so you can get that thick tone.

If you are happy with your Squire, then by no means carry on using it.
ok cool. my next guitar(when mine spontaneously engolves in flames, or i need a new one for any reason) will be a white strat like jimi hendrix. they are so cool lol.

What sort of music do you like to play? Then we can advise you on what amp to get which would fit that genre perfect.