Firstly no, I'm not expecting a Roma Street Parklands for the Gabba. The Parklands is a larger parkland that aims to attract people from a wider area (like the Botanic Gardens (Mt Coot-tha) and South Bank Parklands do, and future Victoria Park will). I'm advocating for a smaller area of outdoor recreation space for the use of nearby residents. A kids playground and/or a landscaped nature play area similar to The Commons at West Village, some areas to lay in the sun and maybe have a picnic, maybe add in a half court soccer pitch to kick a ball around and a cafe, in a site that can be integrated with the public realm areas of the adjacent developed area.
Secondly, you can't compare the high density of Woolloongabba to the sprawling low density of Flagstone or Springfield to Woolloongabba, as that is apple and oranges. We're talking about the population density still being exceptionally close to the station - literally across the road, or maybe a couple of blocks away from the station at most - still walking distance or a short bus ride up Logan or Ipswich Roads on any number of fairly frequent buses. We're not talking about the kilometres of driving that you inevitably get with the low density suburbia and limited PT. If your Woolloongabba apartment is too far from the Woolloongabba Station, say south of Deshon Street (South City Sq) for example, you're closer to Buranda Station anyway.
As for Springfield & Flagstone, Springfield Central has a 24ha park in close proximity to the station with the Robelle Domain & Oasis Lagoon, and Flagstone has it's $12 million regional recreation park across the road from the proposed station location, so there must be merit in locating such park space centrally even out there. The majority of the other surrounding land looks to be used as, or earmarked for, commercial, education or health uses - I guess people don't move to Springfield or Flagstone to then live in apartments.