The one hundred and fifty-sixth TV show: #540 Midsomer Murders
There's the idea that we enjoy scary stories at Christmas because it makes us feel more comfortable being cozy and safe at home. It seems like the same applies to murder mysteries - we enjoy them when they're in these idyllic places where a murder is a big deal, finding all the secrets under the veneer of pleasantness. The series trades on this, always having some secrets hidden under the idea of staying proper and having the calm of their life disrupted.
Aside from that, our lead chief inspector Barnaby is savvy enough to realize what's up, wisely deciding not to actually move to the countryside at one point, with his personal life providing a nice and gentle, less dysfunctional contrast (expect for his attachment to the job). They're all well built mysteries, not jumping in with a murder and not going too gritty even if it goes dark. Add to that that, as with so many British shows, this can be a case of spot the actor, using the same stable so many other shows do, and you can see some actors enjoying getting the chance to play the violent murderer when they'd normally play nice old ladies.
The show does have its issues, with homophobia featuring a bit too heavily in the early murders and the series being too white for too long - perhaps representing some of these areas, but feeding into the xenophobia rooted in these areas rather than challenging it as the show does with this village lifestyle. It's not something that really impacts your day-to-day enjoyment of the series, but it's something you start to notice when you pay attention to it.