Let my just throw my hat in on the side of Jargon. Consistent game terminology makes for a consistent game. Well constructed terminology means a well constructed game. 4e, in my opinion, got it pretty good. As much as people whine about "game-y"ness, 4e's language seemed fairly intuitive to me. Standard actions were what you did on a standard turn: namely hit stuff with magic and weapons. Healing Surge may seem gamey but it makes sense. Its a surge of vitality and will and that galvinizes you into recovering lost stamina (i.e., heal). I would have preferred "Vitality Surge" as a concept and "Vitality/Vitality Points" as a unit of measure, as opposed to Healing and Healing Surge, respectively, what it all can't be perfect.
No, 4e got it pretty good ... but there were issues that plagued it for years, and some still do. How does one wield a Monk Unarmed Strike, exactly? Can you wield two at once? For years we had no idea if keywords were hard-coded or dynamic. Does turning your fireball into a frostball make it gain the cold keyword and lose the fire one? For a while we had no clue. Does it seem like stupid B.S.? Yes. Mostly because it was. But certain moving pieces of the game depended on that stupid B.S.. Do all my feats which effect powers with the fire keyword still work on my frost balls? Do my cold keyword feats work on my frost ball that is counted as a fire attack? Without a clear language its pretty much up to the DM to toss in a hail mary and see what happens. CharOP still doesn't know if a Ranger/Monk can Twin Strike with Unarmed Strike. Most people would admit that they can, but interpreting rules one way has implications throughout the system, and very often a systemically inconsistent system will have counter intuitive results for both interpretations.
Unclear rules lead to an unclear game. Honestly, one of the most horrifying things about that alpha leak a few weeks back was the verbose "can often cast the spell quick enough to still take a full turn" lunacy (well, that and the Christlessly bad monster system). What does that even mean? How often is often? How many "often quick enough" actions can I squeeze into a turn. Can I draw two potions? Ten? fifty? At least minor action was consitent and, to me, intuitive. This just seems lazy and verbose.
I also dread a return to "plain language" spells. Right now I'm preparing for a 3.5 game and am building a Focused Specialist Necromancer, and one of my forbidden schools is Evocation. Luckily, I kept illusion and the wonderful spell Shadow Evocation it has. Now, the thing is, my optimizing wizard-guru buddy says one of the worst things lost by giving up Evocation is Contingency. Luckily, Greater Shadow Evocation fixes this... or does it? See, no one seems to know how Contingency and Greater Shadow Evocation interact. Who exactly is getting effected by the Shadow Contingency? Me? Am I being "effected" by the Contingency? Its kind of ambiguous. I'm weaving magic around myself yes... but it does nothing to me other than cast a wholly separate spell at a later date. So, what does it effect, me or the spell? Furthermore, that just gets silly. I make a will save and if I fail I get to cast my own spell?
Furthermore, how does Contingency interact with other spells? The spell Contingency casts "must be one that affects your person." Awesome. Finger of Death affects my person. Doesn't say I have to aim it at my person. Assuming that doesn't fly (and it probably shouldn't), taking a less obnoxious interpretation, let's say I set up a Contingent Haste. It affects my person... and the persons of my entire party. Does the Contingent Haste effect JUST my person, or does it merely need to INCLUDE my person? If so, if I set up a Contingent Fireball (assuming I have fire resistance), can I take my enemies with me, or does it burn only me and somehow not anyone else for no adequately explained reason? The rules may explain it elsewhere, but there is no bloody way I can tell which is the right way to read the spell just by looking at it, and looking at the SRD, I can't find anywhere where it defines exactly what it means by "affect."
A system with unclear rules is an unclear system. Each one of these questions effects the interactions and tactics available to a party. Can my wizard turn himself into a living booby trap, or set up a surprise speed buff for the party? Or not? Its important that players understand these things, and the simpler they are to understand, the less likely hurt feelings are to arise at the table from "no, that doesn't work and you wasted character resources setting it up" or "Yes it does and your a dumb DM to rule otherwise!" The rules exist to help us determine the action of a world we imagine. If we can't agree on how terminal velocity works, or what chemicals make gunpowder, things get weird quick. So, I say: bring on the jargon! Bring on the manual language! Keywords! Gameyisms! Call it a spell or a power, a vital point or a healing surge! I don't care, as long as you can teach it to me and have it make sense!
