An 80kbps mono station takes 30MB / hour so it adds up if that is your daily commute. That would require me to switch from a £7/month contract for all the data I need whilst out and about etc. (built-in maps help) to something more bottomless - sure maybe only £5/month more but that is still a massive price increase compared to what I actually pay.
Also, you would require an A2DP connection or, worse, a wire - my radio is DAB but doesn't have aux-in for instance - it also doesn't have Bluetooth so I would be shit out of luck.
And I am not going to drive around with a set of cans on head that's for damn sure.
And, I would have to power my phone in the car to avoid pointless battery drain, more hassle unless I paid out for wireless charging in-car too.
I work on car radios and I hear a lot of this FM-is-better-than-DAB but it is not true at all subjectively - especially in a car, BBC Radio 3 (Classical music and speech) will tell you that very quickly, the hiss during the quiet patches are terrible to behold - a reminder of vinyl but without the scratches.
I only listen regularly to one or two DAB stations and the biggest bugbear, for the UK at least, is the lack of stereo but, since my favourite station is not available on FM anyway, DAB in mono is the only choice. It turns out that it is much less of a problem that one thinks.
Adverts, not a fan. Somebody here has worked out a reasonable threshold of adverts to music that I can bear easily and I hate adverts, never watch live commercial TV - pause and delay all the way when I do watch something 'live'. The biggest issue with adverts on the station I listen to the most is that they often place adverts next to something else like traffic or news thus extending the non-music period when it is not necessary - music, news, music, ads please.
I imagine this is for the DJs to get a much-needed longer gap, it's either that or play Bat out of Hell again.