We at ~ThumbApps~ don't just make portable version of any freeware or free & open source software/FOSS.
There are usually some criteria to start a portable work:
1. It's not available at PortableApps.com.
2. It's available at PortableApps.com, but not as full-standalone-offline package—but online installer which would requires Internet connection. Most people don't have that kind of easy and relatively cheap access to Internet—especially in most of developing and usually corrupt... :) countries around the world. These people—including us—prefer to download anything via resumeable and accelerated downloader like FDM/Free Download Manager or uTorrent, for example. Online installer usually just way too slow and unresumeable :(—yes, Internet connection in our countries sometimes just disconnected for no apparent reasons.
3. It's available at PortableApps.com, but we think we can add some value to our version, for example our Opera portable browser—stable, beta, and developer editions—can be updated to the next build from within the portable app.
4. The publisher provides portable version, but some features missing. Like for example Bandizip portable, the official version only in 32-bit and the context menu—which is essential for most users—is disabled.
5. The publisher provides portable version, but it's still unclean. It still writes some settings to the registry and/or Windows data folders.