I remember Phantasie well. I still have 1&3 on my HD. I played 2 on my C64, but it was never released for PC. It was my first RPG, followed quickly by Bards Tale and Ultima!!
*dies of a heart attack*
SOMEONE REMEMBERS PHANTASIE!
My first RPG was Bard's Tale, but Phantasie III came close behind. Both are among my favorite games, though the DOS version of Phantasie III sucks graphically to say the least. ADOM looks like a fancy 3D engine compared to it. One of my earliest memories is of sitting in my grandfather's lap playing Bard;s Tale on the C64. I was 3. He's the one to blame for me having a hundred pages of a design document for an RPG.
Making non-combat skills useful just requires putting in things to do with them. Being able to access otherwise inaccessible areas with climb (or a fly spell), or whatever. Allowing diplomatic negotiations for even random encounters which give the same amount of XP or whatever (same reward for a alternate path). I'd like to go one step further and have more uses for spells than just strict 'do this, do that'. Like using a Fireball to cook a BBQ, or Frost Bolt to create an ice bridge across a river. Not too many games I've played allow multiple ways of using a single spell or ability.
I like the idea of keeping the characters at the same basic physical level throughout the game. I was toying with an xd6 setup. Basically, each race having a set 'health' statistic which determines the number of d6's you roll for HP, add in stat mods. Same for spell energy. However, the highest I calculated in under the current version was 29hp; on a Minotaur. When I had classes, I got to 37 for a Minotaur Fighter.
The problem comes when you have weapons. Most character races have 1 or 2 hit die, so even with keeping all weapons at 1d6 (for 1 handers and ranged, 2d6 for 2 handers) a character could easily die in a single hit.
The characters need to be sturdy enough to survive combat. This is a sticking point with my own design, as currently they basically cannot without a lot of luck. However, too much health, and they'll be too strong and can tank through most combats, and heal up afterwards. Of course, this is using my design as an example; which won't matter much soon as I have a weekend off finally.
So something will change, probably tonight since I took a nap.
Using battlefield tactics can help offset the weaker characters; but that's another topic.
*edit*
I came up with an idea for classes, which appeals to me. It might also appeal to others; but I'm a sociopath and don't care. It's also 2:30a and I worked OT yesterday. So forgive me for being short, or misspelling half my words and having poor grammar everywhere.
Each character starts out able to learn all skills, as a general 'Adventurer'. Later (around level 5) if they qualify, they can choose to enter into a base class.
A base class would give them the ability to raise skills up to 125% instead of 100%, at the cost of losing out on the sheer versatility. For example an Elementalist would be restricted to spells of his particular element, as well as allied elements (more on that later). They might also gain new abilities.
Eventually, a character in a base class might choose to enter into another base class, or even an elite class. This is limited by a max of 2 base classes and a single elite class; and classes whose restrictions conflict cannot be taken by the same character. This is to prevent someone from breaking the who class change mechanic like in DnD3.5. Not to say it can't be broken, but just not that way.
The Elite class would give some more, stronger abilities and maybe cut costs to use others; while upping class skill caps to 150%, and 200% for the class' primary skill (Spellcasting for an Arch-Mage; Lore for an Arch-Druid, etc). The offset would be that it would be even more restricted; the character unable to even use skills not on the class' list; much less learn them. Whereas a base class might restrict learning a skill, but not it's use if it was already known beforehand.
Skills would still be the focus, however joining a class would help define a character more, give them greater strength in that area they already specialize in, and qualify them for even more goodies later on down the line.
One build would be a Rogue+Fighter or Warrior into Assassin. Or a Ranger into Sniper.
The thing would be that while the classes would be there, it wouldn't take away from the freedom of doing what you will; they'd be completely optional.
Which leads to another idea; variable difficulty. Include the traditional mechanics for leveling, increased HP and all, the ability to adjust the power gap between players and the enemy, effectiveness of spells; stackable enchantments; etc... all in the name of making the game truly customizable. Dungeon Hack did this to some extend. This would go a step further with additional gameplay mechanics which would be totally optional. The hardest would be a level-less solo Iron Man run with XP set to 50% (or half gained) and monster difficulty ramped up to 200%.
That would solve any challenge problems as well; if the game has a static difficulty some players will get mad and leave it because it's too hard, others because it's too easy. I remember Devil Whiskey being extremely easy when it first came out; even on the hardest difficulty. It still is easy now, after the rebalancing, but not near as badly. This would put the level of challenge in the hands of the player, not the designer.