“Another reason why B/X is right about everything: the only spells that a new group would have had to learn was Sleep or whatever spell the magic user actually chose during character generation. Most other iterations of the game require people understand the implication of dozens of spells right out of the gate.” – Jeffro Johnson
Every new mechanical ability you give a player makes it that much more difficult for a player to grasp his character’s abilities and figure out a rational way to play the game. I say mechanical abilities, because in an RPG players can and should be able to attempt anything at all; how it plays out is determined by a combination of the roleplayer’s abilities, the system’s mechanics and the adjudication of the GM. The problem with mechanical abilities is that each one entails a rule one must learn and remember to apply in the relevant circumstance.
It can be a lot of fun to play magic characters, and new players are often intrigued by the potential of wizards and mystic types. The difficulty with any class that uses magic (or systems that use myriad skills, non-weapon proficiencies, daily abilities, etc.) is that every spell or ability is a new rule that must be learned and remembered and applied on top of whatever other mechanics may be in play. So not only does one need to remember how to move, how to attack, how to figure out what one’s armor is, or whatever other various tasks fall into the purview of tables and dice rolling as opposed to simply saying “I do/say/look at this”, one has to remember those additional rules pertaining to one’s class; and with any class that’s going to have a lot of spells, that could potentially be a lot of rules. This is one reason why I really like B/X for people new to roleplaying and why I really like low-level play.
I’ve talked about the game I was in where we were all level 12 gestalt characters in 3e; some players were new to the system and everyone but me had ridiculously complex builds* with lots of spells or psionic. What ended up happening was the players had a ton of abilities which they had no idea what they were, how or when to use them, and ultimately didn’t get to use many if any of them. While it’s not as extreme at lower levels in 3e or other systems, there are still going to be a lot spells and abilities and mechanics which new or inexperienced players just aren’t going to be able have enough of a grasp on to play effectively.
My opinions on cantrips and 0 level spells have changed considerably over the last few years. One of my problems with D&D mages was how unmagical they felt and how impractical they were as adventurers, but the weaksauce 1st level one-spell mage really does work both in a lot of settings (especially if you make extensive use of scrolls and adopt some of the implications of the ‘dungeon book’ from Holmes) and in teaching new players the game. That new player who wanted to be a mage? ‘Well, you’re special, so you get one extra rule (your spell) that you need to remember; think you can remember it? Good. If you need to double check, it’s written down.’ But imagine if that player had all of those cantrips (most of which are useless and you’ll find out don’t apply to the situation you want to use them in once you’ve double-checked the actual wording**) and several other spells to start with. ‘Here are all of your spells/abilities. They can be found here, here, and here. Here, they’re alphabetized. Here, they’re arranged by cost. And these over here are sorted by level and alphabetized by level’. You’d better believe that things are going to grind to a screeching halt when that player tries to do something and has to look it up, and he or she will be just as frustrated for the causing the holdup as the other folks will be by the holdup itself.
Having only a few things that one absolutely needs to remember and understand the workings of right out of the gate helps new folks learn the system bit by bit. Learning and acquiring new spells becomes something exciting to look forward to. Players will be excited to have mastered the rule because they’ll know exactly when to apply it, with an ‘aha!’ moment, and will be eager to move into new territory. That’s the difference between magic in a game being fun vs. being burdensome.
*:I actually had to fight to be allowed to play the simple Fighter-Rogue mix; I was strongly encouraged to pick dozens of skills from various splatbooks and use prestige classes and what-not to maximize my character; as it turned out, I was the only player who did not have to go searching through assorted books and pdfs when my initiative came up.
**We can use UA in the AD&D game I’m in, but almost never do. Remembering the mechanical implications of nearly a dozen worthless level 0 spells is more trouble that it’s worth. Phantasmal Force is better than anything else in there anyway, especially since it plays heavily to the aforementioned “players can and should be able to attempt anything at all”.