Football is not 'about more than goals'. It is a game designed for one team to try and score more goals than the other. The key differentiating variable, therefore, is who scores the most goals. That is why goalscorers are the most valuable players on the pitch, and that is why it is preposterous to say that someone is 'just a goalscorer'.
To illustrate, let us take two hugely unlikely but illuminating scenarios A team could complete 100% of their passes across an entire match, win every single tackle and aerial duel, and exhibit some outstanding footballing pyrotechnics. However, this team lack a goalscorer, and therefore do not win the game. Team B, conversely, may have a player who scores 100% of his shots, but this player has something like a ten percent pass completion ratio, gets booked for a bad tackle, and doesn't track back once. This player gets one shot in the match, scores, and the difference is made. I've deliberately chosen obviously ridiculous situations, but you understand my point.
It is of utterly no consequence that Ronaldo doesn't have 'defensive abilities'. He is an out-and-out attacking player, and his job is to put the ball into the back of the net. I do agree that there is a substantial element of aesthetics to football, and players like Ronaldinho come close to amalgamating the aesthetic and the effective, but, at the end of the day, the effective will always take precedence. Nor is it of especial consequence that he stifles Higuain's game, in the same way that, whilst it may be true that Barcelona's defeat of Mallorca suggests that Messi stifles Sanchez and Fabregas, it doesn't matter. A side wants to win, and their best chance of winning is to promote the talents of their best player. I know the idea of a team in which every attacking player gets an equal chance of contributing to the goal tally sounds very nice, but sport doesn't work like that. A side isolates their strong points, and endeavours to emphasise them. Why would Ronaldo - or Messi, for that matter - bother doing defensive work when they are so effective at scoring goals? If tracking back means they are less likely to be in the positions to score crucial goals, it is nonsensical to expect them to do so.
Similarly, it has become somewhat conventional to criticise Messi's 'workrate' (and Ronaldo's, too). It is arguably because Messi runs three or four miles a game (as opposed to the normal six or seven) that he can play almost every game in a season, and make such decisive contributions to every one.
I would also argue that your appeal to an ability to 'take a game by the scruff of its neck' is typical banal nonsense, the type peddled by myopic pundits and pub debaters. If it can be concluded - as it surely can - that the key differential in a match is the goal, then scoring a goal is the most decisive contribution a player can make. Thus, the more prolific and clinical a player, the better he is at deciding games. In England, the ideal performance is the Gerrard v AC Milan performance - running everywhere, tackling, scoring a goal, and suchlike. He turned that game around, yes. But could you honestly say that Ronaldo's goal in the Copa Del Rey final wasn't the decisive contribution? Or that Michael Owen's two finishes in the 2001 FA Cup final weren't the key moments? Or that Lampard's decisive contributions in the 2004/2005 season, regardless of his assists and passing, were the two goals at the Reebok stadium?
If one rates a footballer based on their ability to contribute to matches at the highest level, then it is ludicrous to call Ronaldo overrated. This premise holds if we look at Ronaldo in comparison to past 'greats' - Ronaldo has made just as many decisive contributions to big games as many of the names typically cited.