Picasa is fairly limited, but in comparison, frankly speaking, most camera users are greatly more limited.
Picasa is indeed powerful, awesome even, but oriented differently, in that it helps unknowing beginners to get quite powerful results (if they actually want to try - many still won't). A more sophisticated program is great for sophisticated users, but beginners are not going to get sophisticated results in them. We gotta learn some things first.
But Picasa goes a very long ways towards helping anyone get good results. Most camera users have no clue about even adjusting image brightness, correcting color casts, cropping, leveling horizons, resizing, etc, but Picasa makes it easy, without the user having to know details.
Me, no, I use Adobe Raw, but people with no clue yet just don't adapt that easily. It all can all be learned of course, no big deal except that it requires we choose to learn. Many obviously simply will not so choose. So better than living in the dark, try Picasa. It is free.