Just because you were civil in your expression of it doesn't mean that your opinion itself isn't in poor taste to communicate, especially for someone involved in open source. You may be indifferent to criticism which exists only as a means of self-expression, but when silence costs nothing it's difficult to see exactly how your thought couching your criticism of the e-book ecosystem as a distaste for this long running, free and fairly popular piece of software was going to advance the conversation.
There's a term in Portuguese for a crying baby that's held to a breast but who continues to cry, without even trying to suckle; it's what came to mind when I read your original comment. It's not used for flattery, I'm afraid...
We'll keep using Calibre