I'm torn on this to be honest. With current implementation and visibility of the mines, a HUD icon seems to be necessary to be able to react in time to them. However that also means the mines become hilariously easy to avoid and they become effectively "trash" pickups, rather than anything truly useful.
I'd much prefer if the visibility of the mines, along with their detonation radius would get bigger (damage nerfed though), so they become more of "block the route"/"slow down enemies" rather than "destroy those behind you".
If there would be a perk system, the HUD icon could be one of those perks. Other than that, I'd really prefer better visibility of the mines in general above an icon that does the job for you.