Yes i have the same issue, i think you are expecting that the system understand that if you click the add to cart (the choose options by now) it automatically adds the default variant choosed for it.
This could be good or bad depends on your vision, because if you have a product wich have variants the logical approach is to go inside the product and choose the one that fits your needs based on variants.
I think the problem is not in the way it handles the product with variants but the words on the button.
It could be better if the button instead of say "choose options" says simply "Add to Cart" as the other products then if that product have options it simply behaves as it behaves right now, taking you to the product page.
This could be done with little effort changing this string in the language overrides:
CHOOSE_OPTIONS="choose options"
to:
CHOOSE_OPTIONS="Add to cart"
You can do it form language configuration in the admin pan of the hikashop component.
It works for me and actually i've changed it, is relatively less confusing because if you have products without options theyre going to be actually added to the cart and the client could be disoriented.
Is up to you, if you find a better phrase to put instead of that please let us know!