Lawyers rarely have creative influence on the game itself. But they still fulfill two important jobs in the game industry.

The first is intellectual property (IP) law. Games and all their individual assets are IP which is protected by copyrights, trademarks and sometimes patents. Lawyers are required to advise development teams how to not violate the IP of others and how to prevent others from violating their IP. And keep in mind that games are almost always sold internationally nowadays, which means that an IP lawyer worth her money should not just know about the IP law in the state she is licensed in but also have a vague idea about how IP laws differ around the world. 

The second is contract law. Many game developers are regular employees, and employment law is a whole legal can of worms in itself. But the basics of labor law are usually accessible enough to legal laypeople that lawyers aren't strictly required until there is an actual dispute. And if there is one, then there is usually not much about those cases which is gamedev-specific. But there are also a lot of game developers who don't collaborate in regular employer-employee arrangements. The game industry does a lot of freelance contracting and b2b contracting which require non-standard contracts. Especially considering that game developers sometimes form agreements which are unusual in other industries, like work-for-work or revenue share. Those contracts need to be complicated and non-standard to cover all possible situations, which makes it important to consult contract lawyers. And if those lawyers have a good idea about the realities of game development and game business, then that can be really useful.