In many ways, this reason is related to reasons three and four, and so I have correspondingly less to say about it.
Evangelicals involved in academic pursuits, theology in particular, tend to clump their interests around biblical studies, systemics, and practical areas of ministry training. And the first two among these tend to garner the most interest (for obvious reasons, perhaps). Historical interests tend to limit themselves to the Reformation period, because it is identity-forming for Protestantism, and denominational interests. Again, there are totally understandable reasons for these things. It also helps explain the hiring practices I discussed in my third post. However, it also means that Patristics is a marginal field for evangelicals in theological academics.
This de-emphasis is regrettable, for all sorts of reasons. It skews evangelicals’ broad ability to construct a plausible historical narrative of church history in general, and of themselves in particular. To the extent that evangelicalism wants to situate itself as a historic and confessional Christianity, and to ‘claim’ the doctrinal legacy of the early church (at least in part) for itself, it cannot naively neglect and mischaracterise that past.
It also has a pragmatic effect on evangelicals involved in patristics. Because the discipline is marginalised, research and scholars in it also feel marginalised. This doesn’t have to be so, but I suspect it is broadly so. Patristics is seen as a marginal area, and so not merely its relevance to core evangelical concerns, but its status/prestige/esteem in general is diminished, and those of its practitioners also. And since academia in general, and ecclesial academia in its own peculiar and particular ways, is very much a prestige-game, this marginalises and devalues patristic researchers themselves.
So why go into a field when there are no jobs and no respect and no real place for you in evangelical polite society except as an oddity?