You can increase the UI scaling in options.
However, the UI scaling is limited by the screen resolution to make sure everything fits.
If you are using the minimum screen resolution (1600x900), then scaling is locked to 80%, which causes a small amount of distortion but is still legible, below this, for example at 720p, the scaling is locked to 60% and text is no longer legible. Hence the minimum system requirements.

System Requirements:
Absolute Minimum:
- 64-bit Windows 7 / 8 / 10 OS
- Quad Core CPU
- 8 GB Memory
- 2 GB GDDR5 DirectX 11 Compatible Video Card - NVidia GeForce 660 / AMD R7 360 or Equivalent
- 5 GB available hard-drive space
- 1600x900 Display Resolution
- High-speed Internet Connection
We Recommend:
- 64-bit Windows 7 / 8 / 10 OS
- i7 (or equivalent) CPU
- 16 GB Memory
- Nvidia GTX 970 or AMD R9 390 equivalent Video Card
- 1920x1080 Display Resolution
- High-speed Internet Connection