City approvals for playgrounds can take years to actually build. I've seen projects get delayed or even canceled after the hype dies down. A new swing set isn't going to magically raise your property value by 10%. Kids' noise could actually make your place harder to sell later. I'd wait until shovels are in the ground before factoring it into your offer. Check the city's past projects to see if they ever follow through.
My buddy Mark bought a place near a planned park in Oak Mills. The city said it would be done in eighteen months. Three years later, it's still just a fenced-off lot of weeds. He put an offer in thinking his kids would use it, but they got stuck waiting. Really showed me not to trust those artist drawings they put on the signs. He says he wouldn't factor it in again unless he saw actual construction trucks.
Look at what @wadesullivan shared about that fenced-off lot. Besides weeds, these spaces can attract litter or become spots for late-night noise. You end up dealing with that mess long before any kids get to play there.