Not sure what you mean by part-timers and utility guys. Certainly there are plenty of PT and utility guys by SIM standards who have great range factors. A quick check of OF's alone shows there are 33 with A+ range costing under $1 MM, beginning with Garry Maddox at $300K and change (used to be $200K before the update). They all qualify as SIMS PT and utility guys in my book.
So I guess you're referring to RL utility players. Correct me if I'm wrong (and I may be), but I don't think there are all that many late inning defensive specialists noted primarily for their range. Most players who typically come into games only in the late innings are guys whose overall skills just haven't bubbled up to full time starter level (or, in their waning years, have declined from that level). Some of them happen to have speed and the good range that typically accompanies speed; most don't.
Where these PT, late inning players do fulfill a specialist function, the skill sets that teams look for tend to be hitting, running and fielding cleanly with minimal errors, pretty much in that order. It's very expensive for teams to carry players on their rosters strictly for their gloves, and even more so just for their range.
Who would you consider to have great range whose range factor is screwed by the way SIM chooses to calculate it?