This will enable ability do not calculate checksums for all types of images - known and unknown (with possible warning) - and will speed up writing process for users that don't need extra verification
Or even do not auto calculate checksums for images at all - but instead add button 'Verify image' near 'Wipe USB Disk' and 'Write' buttons - that will begin calculation of checksum and will pop up 'SHA256 Checksum' dialog.
verification is an important feature of isoimagewriter, I don't want to make it easy to turn off