In my opinion Van Haal has done things the right way around - you build a solid foundation that's hard to breakdown and beat and then you work on expressing yourselves from there. United players from the 90s used to talk about winning the physical battle and then the class would shine through and I feel like it's the same kind of principle. For me, it's the difference between amateur level football and professional - lower down the league pyramid you just need one or two creative players and you can tear sides apart and get noticed; but at the very top level of the game you need to get the defensive part right first or else you'll come unstuck against the best teams.
I'd argue it's also the reason people say we're good in the big games but lacked last season against some of the "lesser" opposition. We're defensively sound which nullifies the big boys but we're maybe lacking an edge up front which has prevented us from shining against opposition that are perceived to be weaker. In all honesty, it would be nice to have both, but I'd be more concerned about Van Haal's tenure if we had an attack which looked lively but were leaky at the back.
I'm not convinced that feeling is universal