Roosevelt was on the big government side of the aisle - as such, schemes are necessary to try to get around the constitution aka "the obstacle".
If Roosevelt were "promoting" a better cause, presumably a constitutional cause, then no tactics would be necessary because he wouldn't be employing his lambskin shredder.
By definition constitutional activity is not a tactic.
It passed Congress overwhelmingly. Say it hadn't. Say TR had to reach across the aisle to get Democratic support or had to confuse Congress with amendments and other legislative tactics. Would that have been a good thing or not?
It's easy to take some measure that is unpopular now or was counterproductive earlier and accuse it of being unconstitutional. It's harder if a bill or law expands the size of government but also deals with issues that people think are important and necessary to resolve.
In any case, adherence to the constitution wasn't and isn't the only reason Congress doesn't take action. The power of vested interests is another strong factor.