Flip, Databins allows larger limits for entries with png or jpg images. You can take advantage of this by using the correct mime type in your post request. Or, from a WL interface, you can use DatabinAdd and it will handle all the request forming for you.

Here is a screen shot showing both an http request and DatabinAdd:

You can see here that the size overhead is more modest.

When you use an "Image" interpreter in a data drop webform it imports the file to Wolfram's Image[] format before storing it, which can add significant size depending on the content and original format of the image. That is something we hope to improve.

Yes, it is. I assume the reasons for the limit are that Data Drop is focused on internet of things data (consisting of small and frequent observations), and that increasing the limit would increase the server load and impact the performance of Data Drop.

The 25Kb limit of Data Drop can be bypassed by

1. Using Compress to generate a compressed string of an expression (in this case a figure)

2. Using StringTake or related function to split the compressed string in substrings smaller than 25Kb

3. Uploading the substrings to a databin

4. Downloading the substrings, concatenating them, and using uncompress to reconstruct the original object.