Driving a MOSFET with a lower Vgs than required?
The problem with using the MOSFET under these conditions is that it is very unpredictable how much it will be turned on. The threshold voltage is specified as 4V maximum, however under those test conditions it is only guaranteed to conduct 250 microamperes, and that with 4V from drain to source, which is hardly turned on at all. Worse, that is specified at a die temperature of 25°C and it will be significantly worse at one of the temperature extremes (cold, in this case).

If your design only needs to operate at relatively warm conditions and you only need to switch 250uA maximum then there is probably plenty of margin and it might be considered a good design (other than using a part that's perhaps 100x more expensive and 10x bigger than it could be).
If you are switching more than a few hundred uA and really need to have guaranteed performance (so every item you produce works reliably) then you should operate the MOSFET in or at least near a region where the parameters are guaranteed. In this case, it's Vgs = 10V. A bit more than 10V is fine too.
In this case if you really need to switch such a high voltage you can use a gate driver circuit to get the required gate voltage (and to switch it quickly, so the MOSFET does not spend too much time in each switching operation dissipating hundreds of watts).
If you want to switch a lower voltage (like up to 20-30V), there are much more appropriate MOSFETs available, some of which are guaranteed with 4.5V, 3V or even 2.5V or lower Vgs (so-called logic-level MOSFETS). They also would likely have a much lower Rds(on) than the relatively high 0.27 ohms of this high voltage part.
For example, the very old IRLZ44 has a maximum Rds(on) about 10x lower when driven with 5V than your part has when driven with 10V, and will switch up to 60V.
Many newer parts are much better again.