I'll just use myself as an example. The 2017 HSA contribution limits for a family is $6750. My employer puts in $1200, so I can put in up to $5550 of my own money. Conservatively, if I assume a 15% tax rate, that saves me $832.50 a year in taxes. So, even though the HSA has a higher deductible and OOPM, it has lower premiums (I save $572/yr in premiums), plus $1200 HSA money, plus $832.50 in tax savings assuming I max it out.
All those benefits add up to about $2600 in funds that I have because I went with the HSA plan. The HSA plan has a deductible that is $900 higher and an OOPM that is $2,000 higher. Based on my math, the HSA works for me. At worst, if I max out through in a given year, I'm only $300 behind the other plan.
Again, not saying the HSA is the way to go for everyone. This is just the exercise I went through to decide. I haven't looked into it much, but my expectation is that HSAs are somehow better for the employer than "traditional plans" so they seem to incentivize the HSA plan.
I'd have to look closer to see if it adds up similarly for me. Right now, spouse and I are separate plans. For just me, company will put in $400, $800 for family which doesn't sound as generous as yours. But right now spouse's plan has better everything so it's more likely that I'd move to his if mine goes up much more.