There is no point of getting more skills in drilling since the highest skill needed to use a very expensive excavator is level 19,7
http://www.entropiawiki.com/Chart.aspx?chart=Excavator
Prospecting and surveying will give you more HP also and unlock higher finders to use.
You speak from a skilled player point of view here.
Beginners start at level 0, and it's a long way to level 19.7.
So when one of them wants to get help from the mission, he can't do it for Drilling profession..
And again the question was not to know if you would pick Drilling as reward, but if you think that MA dind't add it on purpose or by mistake.
Also they added Mining skill as a reward for both Ore and Enmatter missions, despite Mining skill is not more usefull than Drilling skill from what you say.
Yes, Prospecting and Surveying also gives HP, but you know that the less point you have, the more HP you'll get whith identical reward (skills in PED).
So for sure I prefer to choose Prospect or Survey at first sight, but if the reward is low compares to my level and then will get me only few points, I would like to choose Drilling that is my lowest one and then get more HP.
The 4 skills gives HP, Prospecting, Surveying, Mining, Drilling.
The 3 first for me are about the same level now, but only one (Drilling) is only half way down.
The 30PED reward would gives me about 1700 points and more than 1 Full HP on Drilling.
When it will give me about 700 points and only 0.4 HP on the 3 others ones.
Furthermore there is alot more missions for Ores than there is for Enmatters, so it will be even harder to skill-up Enmatters professions.