OMS — is probably a core module in execution system. Equity and FX systems tend to need OMS but many trading desks presumably need no OMS, very simple OMS or off-the-shelf OMS. A buy-side trading desk may simply use the OMS of the broker. The same could be said of “execution systems” like VWAP algos.
Therefore, I feel the importance of OMS/EMS is over-stated.
SOR — is more niche, less “generic” a skill, but as a module is more visible to the business.
FIX connectivity — is a more generic tech skill and shows resilience to churn.
mkt data — is more “separate” from the other skills.
