Well, you gain a lot of performance - as much as 10x depending on the complexity of your template. Also, Jinja is a lot less crippled than Django Templates (for example, you can't call a function/method with parameters in Django Templates).
It is 2019 and personally I see no reason to think professional template designers will shoot themselves in the foot if we give them too much power. We are all consenting adults...
https://django-best-practices.readthedocs.io/en/latest/appli...
A common pattern in MVC-style programming is to build thick/fat models and thin controllers. For Django this translates to building models with lots of small methods attached to them and views which use those methods to keep their logic as minimal as possible. There are lots of benefits to this approach.
DRY: Rather than repeating the same logic in multiple views, it is defined once on the model.
Testable: Breaking up logic into small methods on the model makes your code easier to unit test.
I'm glad that Jinja2 templates are now first-class citizens in Django as I care about performance and don't feel like patronizing template designers with a carefully handicapped template language.