As an editor, you may continue to write the odd feature yourself. Assigning the editor to do an interview can sometimes open doors which might otherwise be closed. It can be flattering for the interviewee, especially if it is a rare event rather than a habitual one caused by understaffing. It is also seen as a mark of respect. You must ensure that your performance is up to scratch and that you are rigorous in clamping down on any self-indulgence.
Otherwise, however, you will be assigning writers to jobs, briefing them and editing their copy once it arrives. These are all tasks which need your full attention.
There are times when it is better to use staff rather than freelances. Many types of feature require a great deal of research to produce a very modest number of words. Freelances are generally paid on the basis of what they produce: usually per 1,000 words. This type of article may not be viable for them to undertake, and it is not fair to ask them to do it. But for a staff journalist, the necessary research can be conducted around other jobs, in spare time, and the feature assembled over a long period. This type of job may also need the resources of the magazine's office.
It is also sensible to use staff for particularly sensitive tasks, those which are meant to surprise readers and competitors. Freelances are loyal to your magazine while they are actually working for it: their commitment cannot be expected to go beyond that. Consequently, it is inappropriate to expect them to be bound by silence about your future plans. Staff, on the other hand, should have only one loyalty.
Experimental features which may or may not work, and those which require the daily involvement of senior staff including yourself, are also better kept in-house. One of the central tasks of the commissioning editor is to avoid paying for things that aren't used. But you are paying your staff anyway, and if they have time available it is better to experiment with that.