I'd like to have the picture of each person allocated to a task
While I agree this would make a good option there is a potential issue with the amount of space a photo big enough to be legible would require. Another approach (which I will post as a separate idea) would be the ability to assign a colour to resource in the way that you can now do in MM16 with text tags.
Although it isn't the same as having a photo of a staff member assigned to a resource, one thing you can do is to use callouts. Create thumbnail images of the people involved and then insert into a callout. Resize the image to the size you want and format the callout. Here you have some options - you can go for a minimalist approach with just the image only or you can insert the resource name and/or assign a unique colour for each person.
Either of these approaches allows you to use the power filter to filter by resource name (assuming this is reasonably unique and doesn't for example show up in topic names in the map) or by fill colour. The great advantage of using a fill colour unique to each resource is that the fill colour - and therefore the resource - can be tracked in the Map Index.
I've attached an image showing both options based on the profile mugshots in the Mindjet forum for Andrew Wilcox and me to give some ideas about how this would look (hope you don't mind Andrew! :) Of course you still have to apply the resources tags separately to each task.
One mildly annoying limitation is that you can't save callouts as map parts - if you try to do so they become subtopics. One simple solution is to use the MAP add-in (if you have it) command to Switch Topic to Callout each time after you attach them to topics.