The simple answer in my mind is "No". But, I know life and ministry is anything but simple.
Sometimes, you don't have good choices and you do what has to be done. Maybe you are just staring a ministry and freshmen are what you have....so...they are your leaders. Overall though in an established ministry, I think we do harm when we put freshmen in heavy responsibility roles. My thinking on that was partly shaped years ago when we had a traveling singing group. We did auditions the second week of school...everyone had to try out again. A freshmen girl who was a sensational singer tried out. She was better than the upperclass girl who sang the same part and had been in the group the previous year and been super faithful. The audition team picked the freshman girl. Within a month the freshman girl dropped out of the group and soon was out of the ministry. The upperclass girl's involvement was never the same.
Here's my thoughts. Faithfulness is more important than talent....really! I've also learned that some ministries just offer the same thing each year and consequently that's why some upperclassmen disappear. There ought to be some roles that you have to work up to and earn the right to serve. At one point, we would place sharp sophomores in leadership roles in our Freshmen ministry. Eventually, we decided that was a mistake. They didn't have the maturity to handle it. And, many of them would say after that year that they did not want to serve anywhere else. They had done the "Glamour Role". We decided that was a role you had to prove your faithfulness to be in....not just bright with a great personality.
There should be freshmen specific opportunities. They can be short term and students are likely to be successful. My number one problem with putting freshmen in high responsibility roles is the increased likelihood of failure due to immaturity, etc that may cause them to back away entirely. Freshmen need to be set up for success.
In fairness, I need to say we have lost a few freshmen because someone else would place them in a key role immediately. But, never let faithful upperclassmen feel you do not value their faithfulness!