Great question, this is both an operational and a safety question. Operationally it's hot, very hot, and this is normal. The boiler sits just behind the front panel. On the newer machines, it's insulated. If you have an older model without the insulation, it might seem hotter longer, but it's not an operational problem.
The control board (electronics) on this machine are located at the bottom of the machine, below the heat zone., and the wiring is tin plated rather than less-expensive, un-tinned copper. Tinning ensures wiring lasts longer in a humid environment. Corrosion starts an the ends of a cut wire, and quickly travels down the full length of ordinary copper wire. This increases wire resistance, and potentially presents a fire and operating problem. Tinned wire inhibits that process. Rocket uses tinned wire.
The machine is designed to maintain water temperature just below boiling. It's hot! Yes, the group head has a little "caution" sticker to avoid touching when operating. Needless to say, you want your machine in a location where little, curious hands can't reach. That is a worry if you have children in the house.
The tip of the steam wand is hot, but it's cooler near the top where it first exits the machine. I can move the wand by gently touching that area. Never grab the wand near the bottom with your bare hands. Use a towel instead.
No problem leaving the machine on for hours. However, the manual cautions against leaving it on unattended. There is always a possibility the control board (electronics) fails, which could cause unexpected problems. I turn mine off when I leave the house or after morning coffee.