Earlier this month, national team boss Gordon Strachan claimed Scottish football might need to "manipulate" Hearts, Hibernian and Rangers back into the top flight for the good of the sport.
The three clubs find themselves battling for a route back to the Premiership this season, with the Gorgie club currently occupying top spot in the Championship table.
In his weekly column in the Kilmarnock Standard, Rugby Park manager Johnston agreed the trio were missed.
He said: "Gordon Strachan had his say on the subject last week and thinks for the top league to prosper it has to have Rangers, Hearts and Hibs back in it.
"I think he’s probably right, there’s no denying that they are three massive clubs and if they were back in the top flight then we would have more chance of getting extra cash into our game.
"Those three clubs are really important to Scottish football and as well as sponsorship it might help with TV money – it’s easy to see how important the millions of pounds are down south from TV revenue."
After years of talks over league reconstruction including a failed vote to implement a 12-12-18 league structure, the SPFL was formed which retained a 12-team top flight with three lower leagues of ten sides.
Johnston questioned whether the new body any made any difference to the way the game has been run, adding: "we still don’t have a sponsor, which is criminal for one of the top leagues in Europe."
And having played in England with Sunderland and Middlesbrough, the 40-year-old has called for a bigger Scottish Premiership.
He added: "I think a bigger league would have a massive impact. At the moment, you’re playing teams three, four times a season – sometimes even five when you count the cup competitions – and you become familiar with the players and the way that teams play.
"If we had a league of 18 or 20 sides and you were only playing each other twice a season, it would improve what’s on offer for players, coaches and fans.
"Personally, from playing in England, it’s a completely different beast down there. You’re visiting different stadiums, playing different teams – that’s what it’s all about.
"I’m sure as fans it must be much better playing different teams and visiting different parts of the country, rather than going to the same places all the time.
"Last year we played Dundee United away three times when you include the Scottish Cup tie. Something needs to change.
"And I don’t think I’m alone in saying that with everyone in Scottish football airing similar views at the moment."