There was a time when the primary purpose of the LCMS system of higher education was to prepare church workers. Seminaries produced pastors, our colleges produced teachers, other professional church workers, and prepared for seminary. For good or for ill, those days are gone.
There are not nearly enough church work students to support our colleges. If we were to revert to church worker training we would need to close at least half of our colleges, I would estimate, maybe more, for lack of students.
So the mission has expanded. Our colleges have added other courses of studies and generally they are surviving, even thriving. It is, I judge, of benefit to the church to provide opportunities for our young people to have the opportunity to receive a good education in their chosen field in a Lutheran context. It keeps our colleges active. As to whether the LCMS should subsidize our colleges for training for secular vocations, How much does our Synod actually subsidize these schools anymore? I don't have exact statistics, but of the LCMS elementary schools it is typical for half or more of the students to not be members of the supporting congregation. Is it fitting that congregations subsidize the education of students who are not members? Think of it as a mission opportunity - and one that is partially funded by the mission prospects.
Seminaries are, or should be, trade schools first and foremost. They are to prepare students to be pastors in congregations. Now, proper preparation should include a number of things, one of which is an academic background in theology so that they can be a theological resource for their congregants and that they can be knowledgeable member of the Church. Balancing the need for academic excellence with the practical needs of pastoral formation may not always be easy. Trade offs are necessary. And some students are likely to be better suited for the life of the academy than the parish. I remember one prof when I was in seminary that I thought was the poster child for requiring parish experience of sem profs, but what parish would you want to sacrifice to give him that experience, and I doubted he would have actually learned much other than that parishioners can be stupid, ignorant and stubborn.
Again, there is a place in the seminary for the academic pursuit of theology, both to provide background for pastors to be and for those who are suited for academic theology. But if a seminary envisions its mission as primarily turning out academic theologians, it has failed.