I'm not sure that "size matters" here means "small is better than large". But with a modular design where you can swap parts in and out, how could you ever change the size of your screen if you want a larger phone?
Not sure about increasing the size but being able to replace/fix a broken screen would be huge. I'm no hardware engineer but I would suggest that making the phone/screen bigger would in fact be possible, if the modular platform was designed to accommodate.