The last time I ran a game with Mages in it, they were obsessed with only using rotes, leafing through the book to see how they could combine their magic to cast Rotes. They never once even considered casting a spell that wasn't a rote. It wasn't something they roleplayed; they played as though anything but rotes was bad and wrong, and not how spells should be done. I'm guessing this attitude was based on their previous experience in D&D, where pre-made spells are the norm.
So next time, how should I get the players to be a bit more adventurous with their spells? Or should I let them play in this more confined way, if it's what they as players want? As far as I'm aware they knew they could do non-rote magic, but we were all fairly unsure how it all worked when we first played. I don't think it was ignorance that they could use magic that way, but perhaps of how interesting and powerful it could be.
Best Answer
Let Them Be.
There are practical reasons why mages and players might choose to rely on rotes. Improvised spells not only have a smaller die pool (Gnosis + Arcanum vs Attribute + Skill + Arcanum), but they have a mandatory cost of 1 mana if not in your ruling arcana. If your troupe is more interested in collecting codified effects rather than doing spontaneous magic, that's great news for you — you can motivate them with the "carrot" of access to new and interesting spells that they might not have thought of, and they'll be quite excited to join a Legacy where their favorite spell is now simply part of their being.
However, to advance your position, occasionally remind them that something they want to do could be accomplished with an improvised effect. Not constantly, but contextually, as they find themselves in trouble.