I think the small map is in response to criticism that the game can be a running simulator at times. Smaller maps allows for more potential engagements with enemies while limiting repositioning time.
This is something I think Fortnite does really well. You don't need a vehicles to get around.
You are right about the running simulator comparison, but still.. Fortnite is no game for me. No vehicles, no add-ons, the ridiculous building feature and the simple combat. Fortnite is meant for the PlayStation 4 and it should stay there. PUBG may have it's glitches and flaws but I really prefer it over Fortnite.
I do agree with you on Fornite. I've never liked it. Its a over simplified version of PUBG but I think people like it because its less serious and more colourful. The building mechanic is interesting though but I feel its to easy to spam walls around, you reducing the need for better tactical positioning. Also I hate the 3rd person aspect of it, but the time to kill is higher so its impact is less apparent.
I do disagree however that its meant for the PS4 based on its simplicity. Its just a simple game in general.