" Off the Rack " Logic ...
There's only so much display space at the big box golf stores.
The club manufactures (Ping, Calaway, Nike etc.) cannot afford to create personalized clubs for display on the walls for you to have a complete choice of shaft flexes, grips and swingweights. That's just plain smart economics and still trying to do the best for the customer without going overboard. It's not perfect, just effective.
Those " off the rack " clubs were designed by the big manufacturers for an average person. There's nothing wrong with that unless you're taller or shorter than 5'9" and a 35" length from your wrist to the floor. Any differences ( i.e. taller or shorter ... longer or shorter arms ... anything not average in your swing speed (~85mph) etc. ), and automatically there's a problem with the lie of the face of the club. It's not what you need it to be and possibly the shaft flex is limiting your distance, based on your swing speed.
Is it wise to purchase clubs that may limit your success? We'd suggest paying less, receiving more (our advertising budget is very low) and being fitted to achieve your best game possible and make it all fun again.