Yes, black simple T-shirts can be suitable for summer depending on personal preferences and the climate of the region you are in. While black tends to absorb more heat from sunlight, making it feel warmer, many people still choose to wear black T-shirts in the summer for various reasons.

Here are some factors to consider when deciding if black T-shirts are perfect for summer:

1. Heat absorption: Dark colors like black absorb more heat compared to lighter colors. This can make you feel warmer in direct sunlight or hot weather conditions. If you live in a particularly hot and sunny climate, you might find lighter-colored T-shirts more comfortable.
2. Personal comfort: People have different tolerances to heat, and some individuals may not mind wearing black T-shirts in the summer. If you feel comfortable and confident in black, you can certainly wear it during the summer months.