There are a number of reasons why we don't built Texas-esque style interchanges in Canada.
As others have mentioned, the largest reason is probably winter maintenance. Structures require a lot more preventive maintenance in northern climates than they do southern. Not only does this maintenance carry significant monetary costs, but it also has significant traffic impacts. Look at the delays that have been caused just from the single lane closure of the ramp from the eastbound 401 to the northbound 427.
For Houston in particular, Houston is quite flat, so it is impractical to bring large quantities of earth in for fill, as there is simply not a lot of land that they can borrow from. Trucking earth is an expensive proposition. You can see this in Ontario as well, the grade separations along the 417 between Ottawa and Cassleman tend to be elongated in order to minimize the amount of fill that was brought in for the bridge approaches.
https://www.google.ca/maps/@45.349373,-7...3m4!1e1!3m2!1sW8v81HYu8mTr88jxMMsg3w!2e0
The final reason is drivability. In places where the ground doesn't freeze you can build sharper curves with greater super-elevation than you can anywhere in Canada. In Texas, for example, curves can be super-elevated upwards of 8%, where as here we generally limit ourselves to using less than 6. Furthermore there is also the reality, that bridge decks will freeze before other sections of road, which is further incentive not to build long bridges with sharp curves.
One thing that should be noted, is that despite their massive appearance, interchanges in Texas often have a much smaller footprint than their Canadian counterparts:
High 5 interchange in Dallas:
400 and 407, same scale: