It would be possible, and not too hard technically to build a reasonable quality intrinsically safe camera. Today's low voltages make things a lot easier as potential spark energies are proportional to the square of the voltage.
However intrinsic safety is something that needs to be designed in from the start, which probably isn't viable for the limited market of hazardous area digital camera, so the cheaper way is to make it extrinsically safe with a big heavy case, possibly filled with sand. There are various classifications for different environments, but it's not just a case of having a sealed box - it has to stay safe when dropped, and in some cases, testing assumes it gets full of gas and then ignites, and no flame must come out.
Once you've gone through all the approvals hoops, it is time consuming and expensive to change anything without jumping through most of them all over again, so a product needs to have a long lifetime, which is why this one uses an ancient camera design.