The way I think about writing for brass has evolved over the years, especially for the instruments with which I'm not intimately familiar. One hopes to keep learning new things, and to learn from previous experiences.
I used to write a lot for the piccolo trumpet in my arrangements, and still use it quite a bit. But really, I mean, a lot. I had the good(?) fortune to write for a couple of guys that loved to play piccolo and it colored my judgement. I've since learned that piccolo trumpet is like curry. A little bit goes a long way.
So when I start a chart, the template is e flat trumpet on top, 2 b flat trumpets, and flugelhorn. You can see my previous post One on a Part and begin to get a sense of why I like the e flat trumpet (but I'll write more about that later). Generally, I'll not notate anything higher than a 'g' (first space above the staff) for the e flat trumpet. If I need to write higher, or if the tessitura of the e flat part is hovering around the top of the staff all the time, then I'll consider switching the second player to piccolo and taking some of that hovering high tessitura away from trumpet 1. I'll also go back through the e flat part and see if it doesn't lay just as well on a bigger horn; but using e flat is usually a color choice.
So putting the piccolo in the 2nd part is about imposing writing discipline - it keeps me from automatically making the 1st trumpet part a screamer.
That's not about patronizing the trumpets - it IS about the reality of the physical aspect of trumpet playing and hoping that more than one of my charts might appear on a program. Every once in a while, I'll crack off a piccolo trumpet feature. But for me, generally, writing for piccolo trumpet is purely a color choice and now more about comfort and security of the tessitura in a part than it is about writing high notes in the chart.
That's a really important distinction.