It was veeeeery painful to find the root cause of one error in mobile Android application because programmer doesn't have Object Spy in his computer so he had to create at least 15 builds of applicat...
I requested this feature quite a while back as well (ver 7 days !). It is often critical to use the object spy on PCs that have only TestExecute installed. This allows for faster and targeted triage of issues encountered during test runs.
My preference is for a standalone utility as first preference, and object spy as part of TestExecute as a second choice.