Bollards are booming since the 9/11 bombings in the United States and more recent vehicular terrorism in London (and elsewhere). Bollards and other defensive architecture may protect buildings and sidewalks from vehicles, but they typically don’t encourage people to come enjoy public spaces.
Jersey barriers are probably only redeemable by really great graffiti or art (you decide what the difference between the two is), but one Dutch company has created some ways to turn bollards into places to sit and bounce .
Northfield is small enough and safe enough to avoid most of the security bollards, but maybe Sechler Park could use some improvement along the trail: