Johnny has not had excessive amounts of screen time. He is finally getting some resolution for a long running, slow burning storyline that started back in January; that was a whole six months ago. He has had two big weeks in total before recent events; the week he came out and the week that The Albert opened. Other than that he's very much been a supporting character. Now he's being focused on in order to finally resolve the ongoing storyline with Linda so that the storyliners can get both characters to a point where they can move on to new things. Absolutely nothing wrong with that.
As for the comments about Sam Strike being a bad actor, well, I respectfully disagree. He's a young guy that's obviously very passionate about acting and this is the first time he has ever done serious drama. He's not always perfect but he has an extremely expressive face, works well with anybody he acts alongside and is improving his physical presence all the time. He does emotional scenes very well, as well as the more light hearted ones. And it's not down to his looks that I'm saying this, otherwise I'd rate Ben Hardy far more highly than I do.