Reinforcement is just that. Not haveing seen the joint I would imagine some one has attempted to prevent a common point of failure.
The material used to manufacture it is as every manufacturer of any thing the most cost effective they can find (the cheapest) and meets the minimum requiments. There is also the fact that we as innocent as we are don't always use purchased items in the manner the designers intended it.
It boils down to how much you are willing to pay or adhear to the designers precautions.
If you are comparing company "A" product to company "B" product and both are nearly identical designs except one has the welded braces, then it may be safe to conclude that the one with welded braces is stronger (assuming good quality welds). However, if one is made of thin members with bracing and the other is heavy duty, stout members that are unbraced, then it is not a trivial excercise to figure out which will be stronger. Bracing can be a cost effective, low weight method of supplying strength where it is needed most, but it is not the only way, or necessarily the best way to design something to meet required strength. It is also not necessarily an indication that the rest of the design or workmanship is "bad".