R-Type Final is an amazing game, I love every pixel of it.
Thing is, many shmup fans are into more manic stuff at the moment, like ProGear and other bullet-crazy Cave games with non-stop action and insane scoring options. Games like that follow a radically different system than R-Type Final with its good ol' pattern-/memorization approach.... a different "school of shmups", if you will.
What's more, R-Type Final has limited credits at first, so you simply have to play and learn it for a while until you are either able to a) beat the game on 1 token or by using the exisiting credits, or b) play it long enough to get more bonus-credits and other hidden extras that may keep you playing to get them all. Either way, if you really want to get somewhere, you have to memorize patterns and learn how to beat/dodge/manoeuver through bosses, narrow flight pathes packed with enemy installations or tricky bullet sprays. Other than that, it's virtually impossible to beat the game because it follows the classic R-Type formula: You won't go nowhere with sheer firepower alone.
That's not to say you could clear those manic games by simply collecting lots of powerups and then cheaply blast through huge clouds of enemy ships, but compared to RTF, they feel more accessible, specially to those with short attention spans...
Irem tried to adress this "problem" by adding unlockables to Final, bonus ships, gallery pics and so forth, and there are some nice bonusses involved if you beat the game. You'll get most of that stuff even if you don't clear it on one credit/one life, btw.