Chalko I can posit a few: no cams, body sensors, calendar, call logs, contacts, mic, etc on a wifi hotspot to hack. texts to and from the data sim are possible and may be exploitable but there is an extra layer of separation between actual phone and internet. yes, you may have a sim registered to you, but attack vectors are severely curtailed. proper care with vpns and ip number/more anon messaging can make it significantly harder to identify or intercept. prepaid options also exist, for another layer of anonymity, if properly maintained by usage habits.
But yes, one has to keep up with two devices. OTOH, the hotspot can be left some distance from the phone an still provide signal.