Well, let's compare the two spells:
Here is yours, Increased Load (IL):
And Enhanced Ability (EA):
View attachment 130549
Level 1 (IL) vs. Level 2 (EA) - IL is better
Range 30 feet vs. Touch - IL is better
Casting Time 1 action (ritual) vs. 1 action - IL is better
Components both VSM - no winner
Duration 10 minutes vs 1 hour (both concentration) - EA is better
Both allow double carrying capacity. Now, as you say you are restricting the Strength ability checks advantage to only carrying and lifting, but a creative player could apply that to things like grappling ("I want to lift him over head and throw him!") and it would easily apply to feat such as lifting a gate or something.
EA has the benefits of more universal application of advantage, and you can have it work for ANY ability score (not just Strength) as well as affecting more than one target if cast at higher spell level. But since the Strength component in IL allow continuously heavier loads with higher level slots, it can make you
stronger than EA.
IL is better in many ways at doing what it does (more focused) than EA, and as a ritual can be used over and over without hindrance. Rituals, IMO, are one of the most powerful features for Wizards, and this would certainly be a boon for them IMO.
IDK, given that Enhanced Ability already exists, I can't see a good reason for such a spell... but YMMV of course.