I love how people complain that there's no mid-range items between "casual" and "hardcore," then we have this thread complaining that what is commonly seen as casual is not casual.
Make up your minds.
Earning alexandrite in and of itself is the definition of casual. The materia melds are expensive not because of a design choice by SE, but because of market values. If you want THE BEST MOST UBER of weapons, you have to be willing to pony up the dough. However, getting materia is very easy. You can get a full set of very nice shiny materia with a decent shot at the more expensive ones if you're willing to invest the money or time.
"Casual" does not necessarily mean it can be done in a week of playing an hour a day. That's absurd for a game's endgame content. Hell that's bad business sense since if it takes a week to accomplish something, what are your casual players going to be doing the other 5-6 weeks between major content patches?
Things take time. It's a purposeful design decision to keep you paying your monthly fee. Deal with it, or quit. Time investment isn't going to change.