Although motor imagery-based BCIs have been demonstrated to be relevant for improving motor recovery after stroke, they remain barely used in rehabilitation services. We hypohesise that acceptability (which is assessed in terms of perceived usefulness, ease of use and intention to use) could serve as a lever for fostering the adoption of BCIs through the improvement of their efficacy. More precisely, we suggest that improving the acceptability of BCIs could alleviate post-stroke patients' anxiety, stimulate their motivation and engagement in the BCI process, and thereby, favour skill acquisition (here self-regulation abilities), which will ultimately have positive effects on motor recovery. We created a model of acceptability of BCIs specifically for functional rehabilitation after stroke, and designed an associated questionnaire that was used to empirically assess the weight each factor of the model had on acceptability. Hereinafter, we introduce the methods and results obtained based on the responses received from 140 patients, and compare them with data collected in the general public (N=753). In a nutshell, for both the general public and patients perceived usefulness, scientific relevance and ease of learning emerge as the most influential factors.