Should the Apostle Paul been a bit more succinct?

[Statilius the Epicurean]

Hemmingway hadn't been around yet, sadly.

Seriously though do you have any passages in mind? I don't think anyone will defend Paul as a particularly polished stylist, because he wasn't. He lacked the education in Greek rhetoric that was expected of authors at the time and was writing his letters extemporaneously. And scholars think some of the letters we have are multiple ones stitched together, which might explain things. But I don't know if it's a problem of Paul not being succinct enough necessarily: if anything he's sometimes too succinct on important issues. And certainly not prolix in comparison to classical rhetoricians like Demosthenes or Aelius Aristides.

[Statilius the Epicurean]

Galatians 3 seems quite well structured to me: Paul presents his argument, admonishes the Galatians for doubting it, gives a scriptural justification, responds to a couple of objections and then closes with an elucidating metaphor and a rhetorical flourish. I don't quite see the rambling there at least. As a modern Christian it might help to keep in mind that Paul is writing to a church he had to convince, not merely say "we're justified by faith not the law" and leave it at that. Paul was embarking on a highly controversial theological reinterpretation and wasn't necessarily considered an unimpeachable authority by his audience. He had to be more detailed in his arguments than what a modern Christian might require.  

Romans 8 is just a beautiful piece of writing. The entire point of the chapter seems to be a bit flowery in order to give the Romans some comfort and hope amidst the unrelenting discussion of sin.