tinyE: As a child of the 80's I think this sums it up. :D

groze: My opinion isn't worth much, but I truly think there's some kind of ratio between the amount of money and publicity it takes to make a game and the difficulty.

Old games were expensive to make, at the time, but people hadn't spent loads of money on a computer in order to play them "in all their glory", like what we have today. You had to invest on a good rig, for the time, but it wasn't like today, in which you have to spend a whole deal of money on a gaming machine. I guess it doesn't feel right for developers to offer an experience that is so difficult that's almost impossible to people who paid lots of cash in order to have a computer capable of running the games. If we pay a lot for our computers and, on top of that, have to pay a lot for the AAA games, it makes sense that at least they're "finishable", I think? It's a stupid theory, but it makes sense to me.

Old games were harder because we had less money to invest on them (I speak for myself, at least), and we had to replay them over and over again because we had nothing else to play. I usually made breaks between particularly hard games and started playing other hard games I had put on hold, that's how I eventually got to finish them all, because some times it got downright frustrating, and interspersing my few video games was what got me through them. To be honest, I still do this nowadays, so, I don't have a "backlog", I keep playing everything I have at intervals.

Strijkbout: Difficult or not I wish there were more games like Raptor.

By the way my theory on why old games are more difficult than most of todays comes from the fact that gaming originated from the arcades and were designed to suck up your coins in the least amount of time.
Compare Raiden with Raptor, both are similar games though I find Raiden waaaay more difficult than Raptor as one projectile instantly kills you, Raiden was originally an arcademachine game and Raptor was designed as a homecomputer game from the start.

DarrkPhoenix: The laser turret is certainly nice for most of Tango sector (it's the second step in my usual upgrade sequence, after the minigun), but once you get to the Outer Regions the damage output isn't enough to take down the waves of air units, and it's completely useless against most of the bosses (them being ground units), so make sure you're saving up enough money to grab the Twin Lasers by the time you get there. Also make sure you have some air to ground missiles you can quickly switch to whenever you need to take out ground units in Tango sector.