I love the idea and implementation of the Arcane Focus....just not at 1st level.
House Rule: As a spell caster progresses in level and net-worth, they can seek to make an arcane focus, buy one or receive as a gift. Entry level Arcane Focuses will have a "per use limit" because they will be constructed of simple materials such as wood, leather, bits and baubles. Higher level arcane focuses will have more "per uses" and made of better quality. In time a spellcaster can acquire one of the highest level Arcane focuses and it will have infinite uses.
Thoughts that support this rule: Spell components have always been a fun part of my campaigns. For instance, they limit the infinite power of spellcasters by requiring them to obtain and maintain the required "ammunition" needed to cast their spells. This encourages the players to develop a strong rapport with local merchants that can provide these components (both common and rare.) In addition, it supports the local, and regional economy. Vendors who sell such components are always willing to pay enterprising adventurers that can bring them components. Lastly this is a great campaign hook when a local adventuring band has enough reputation to catch the attention of high-level sages or spellcasters who are willing to hire them to go into the lairs of rare monsters, slay them and bring home their bones!!