A better design would probably divide the heater element into 3 or 4 sections, and possibly add a few thermistors, and thus be able to keep a relatively constant temperature (or any other desired heat profile) on the sensor. As it is, the sensor will be at varying temperatures along the single heater winding, depending on the heat load/loss for that section of heater element.
Isn't it just a maintenance and reliability issue? A constant-on heater is much more durable and safer than one fitted with sensors. Thermistors do break down (at least they do every two years or so in my tumble drier). I think it will be quite difficult even with modern technology to design a IAS meter as maintenance free and reliable as the 200 year old Pitot rubes.